Green Practices for the Reconnection of the Historic Urban Fabric: A Case Study of Naro (Sicily)

Abstract

Minor Southern Italian population centers present a fragmented and uneven urban landscape, resulting from abandonment and depopulation phenomena that have led, especially in historic city centers, to urban voids scattered with rubble, buildings in a state of ruin, and others with evident structural collapses. Within a broader urban regeneration strategy for these centers, aligned with current national and European policies, the recovery of these vacant spaces can play a decisive role in enhancing urban quality and the desired touristic appeal, with social, economic, and environmental implications. These areas may also become valuable resources for innovating the urban core in a green transition process, contributing to carbon neutrality goals while improving residents’ quality of life. This paper addresses the importance of pocket parks as systems of resilience against climate change and hydrogeological risks, as well as rainwater drainage systems in densely built urban areas with strong historical character. The study includes a case study application focusing on a location in the Sicilian hinterland, notable for its historical and architectural value. The urban center under examination, Naro in the province of Agrigento, has experienced significant depopulation over the past fifty years, and the designation of its provincial capital as the Italian Capital of Culture 2025 could provide the opportunity for revival through small-scale, low-cost, and sustainable actions.

1. Introduction

The constellation of minor centers with less than 10,000 inhabitants accounts for 84.7% of the current 7896 Italian municipalities, covering 70% of the national territory and hosting 30.4% of the population—these figures highlight how these minor centers represent a significant component of the Italian landscape. Beyond the differences stemming from their heterogeneous territorial contexts—whether geographical or socioeconomic—the characteristics and challenges of minor centers in mountain areas differ or even contrast with those of coastal settlements.

Since the post-World War II period, while coastal centers have generally experienced rapid population growth and consequent urbanization—often marked by poor-quality construction and, especially in southern Italy, episodes of illegal building—the transformation of inland minor centers has been modest and relatively slow. In many cases, their current urban footprint differs little from that of their historical cores, as no significant expansion has taken place [1]. Except for limited cases, these centers present several shared issues of ongoing demographic and economic decline: high unemployment rates, significant loss of young population, chronic lack of essential public services (such as healthcare and education) accessible within reasonable timeframes, and the digital divide, which compounds geographical remoteness with a “virtual” distance, further hindering efforts to achieve social and territorial cohesion. Moreover, they often lack adequate mobility and public transport infrastructure [2].

In Sicily, the framework of 391 municipalities includes 285 minor centers, scattered throughout all provinces, with populations not exceeding 10,000 residents. Among these, 52 are coastal and 233 are located in the island’s inland areas. As in other southern Italian regions, the transoceanic migration flows of the late 19th and early 20th centuries were followed, after WWII, by further population flows: from inland areas toward provincial capitals and coastal towns on the island itself, or the industrialized cities of northern Italy and continental Europe in search of better opportunities in employment and education [3]. This migratory phenomenon, which peaked sharply during the postwar period (particularly between 1951 and 1971), has continued—albeit with fluctuations—up to the present day [4]. While coastal areas continue to attract residents, the vast majority of hill and mountain minor centers fail to appeal beyond their municipal boundaries.

Generally, minor centers in inland areas show a low level of local planning capacity, due in part to limited administrative competence and, in part, to weak entrepreneurial dynamism. Except for a few cases, local development policies pursued by those minor centers that have attempted to counter their geographical marginality from productive areas have mostly been low-impact or constrained by EU funding cycles and deadlines, yielding questionable results.

Progressive depopulation has led not only to the physical decay of unused buildings, but also to the near-total absence of real estate investment by local residents, who typically fall within lower income brackets. These structural issues produce negative social and economic effects, resulting in national costs tied to vast underused or entirely unused territorial capital [5,6]. The island’s inland areas are marked by a significant presence of high-value territorial resources. These derive from the diversity of environmental and landscape configurations—featuring unique flora–fauna systems and geomorphological characteristics—and from the historical processes of human settlement, including agricultural activities developed over the centuries [7].

The settlement system of inland territories consists of hill and mountain towns, almost always established in the Middle Ages, whose foundation was often linked to military control functions, as evidenced by the widespread presence of castles [8]. A network of ancient territorial routes connects these towns, branching across landscapes dotted with villas, farmhouses, archeological remains, churches, and hermitages. Together, they form a historical and cultural heritage of great relevance, largely abandoned and underutilized.

Recent strategies aimed at revitalizing inland areas aim to reverse current demographic trends by attracting new residents and slowing the exodus of the current ones. These strategies are rooted in the awareness that no social regeneration can occur without revitalizing local productive activities and ensuring access to essential public services (healthcare and education) and collective mobility infrastructure.

The challenge lies in promoting residential and economic development to reimagine the role of local territorial resources, integrating them into contemporary contexts through innovative projects. This development approach—centered on enhancing endogenous housing and productive values—sees residents as key actors, along with newcomers attracted by the qualities and potential of these territories. The goal is to foster a dialog between rooted traditional knowledge and new external expertise [9,10]. In this light, one of the many objectives for regenerating minor centers in inland and marginal areas could be the exploration of the characteristics and potential of their urban fabric, to identify design solutions that can reconcile historical–cultural demands with the needs of contemporary living, while promoting social inclusion, sustainability, and innovation.

More specifically, this paper aims to examine the current and potential role of outdoor spaces identified as “urban voids,” whose origin may stem from various causes. The issue is addressed experimentally in a specific case study: Naro, in the province of Agrigento. This urban center of about 7000 inhabitants is chosen as representative of all those minor centers in the Italian hinterland located in a marginal position with respect to medium-large cities and which share, on the one hand, the same problems such as lack of services and depopulation and, on the other, the presence of an architectural heritage of considerable historical and artistic value, even if often in a state of decay.

The research is part of an agreement between the Department of Architecture of the University of Palermo and the Municipal Administration of Naro (Ag) in response to the Administration’s desire to promote measures to enhance the town center. The urban greening initiative aims to redefine various abandoned spaces that lack a clear identity, creating new opportunities for their use.

The research has made it possible to select some open areas within the historic urban fabric, often generated by collapses or demolitions, whose perimeter is formed by the remnants of now-absent buildings or by footprints of structures that have completely disappeared. This refers to degraded and abandoned areas, whose presence may trigger further deterioration processes and diminish the value of surrounding buildings. Urban voids may also include residual spaces within blocks, overgrown green areas, or broad clearings at the edges of denser developments—open areas often used for improper functions (such as parking), which are essentially unplanned spaces.

As part of a broader urban regeneration strategy for minor centers in inland areas, revitalizing urban voids is a widespread, targeted operation of reclaiming, reactivating, and repurposing unresolved spaces within the urban context. This revitalization is also an opportunity to expand and enhance the provision of green public spaces (typically scarce in historical centers), through design choices that address urban climate mitigation, air quality, livability of compact cities, and environmental sustainability.

2. Green Solutions for Urban Regeneration

Urban green planning is recognized as a global priority. Management of natural areas and ecosystem services is essential for restoring nature and allowing a new prosperity of biodiversity. Especially in dense urban areas, green infrastructure offers a fast and cost-effective solution for absorbing and storing carbon. This topic is at the core of European policies aimed at countering the impacts of ongoing climate change on the urban environment. The EU Biodiversity Strategy for 2030 is one of these key policies, and its cornerstone is the first-ever Nature Restoration Law, which concerns the long-term recovery of biodiverse and resilient ecosystems.

Restoring nature plays a vital role in slowing global warming and thus adapting to climate change and mitigating the impact of natural disasters. EU Regulation 2024/1991 establishes a framework within which Member States must ensure no net loss in the surface area of urban green spaces and urban ecosystem areas. Starting from 1 January 2031, the regulation invites Member States to increase the surface area of urban green spaces through expanded tree canopy coverage, the integration of green areas into buildings and infrastructure, and the enhancement of urban ecosystems [11]. The European Commission’s communication of 24 February 2021, titled “Forging a climate-resilient Europe—the new EU Strategy on Adaptation to Climate Change”, emphasizes the need to promote Nature-Based Solutions (NBS). It acknowledges that economically efficient climate adaptation can be achieved by protecting and restoring wetlands and peatlands, developing urban green spaces, installing green roofs and walls, and sustainably managing green areas and farmland.

Urban ecosystems—such as urban forests, parks and gardens, urban farms and allotments, tree-lined streets, meadows, hedges, and ponds—generate numerous benefits in dense urban environments [12]. Healthy urban ecosystems are also essential for supporting the vitality of other key ecosystems by offering shelter and breeding grounds for bird species and pollinators associated with agricultural and forest habitats, as well as important habitats for migratory birds. In densely built areas, greenery can have a measurable impact on the local microclimate [13,14]. The ability to regulate temperature is enabled by the exchange of water vapor between vegetation and the atmosphere through the combined effect of plant transpiration and evaporation of water contained in plant tissues. This process, known as evapotranspiration, helps counteract the urban heat island (UHI) effect in highly built-up zones, where solar radiation is heavily absorbed by heat-retaining materials such as asphalt and concrete, leading to significantly elevated temperatures.

The most common source of noise pollution in urban centers is traffic, and vegetation barriers are effective in attenuating it, especially by reducing high-frequency noise. A vegetation barrier’s width is directly proportional to its noise absorption capacity. Numerous studies have investigated the benefits of vegetation in filtering air pollutants [15]: planting greenery in street canyons can reduce ground-level concentrations of nitrogen dioxide (NO₂) by up to 40% and particulate matter (PM) by up to 60% through air biofiltration. This process occurs through a cycle of simultaneous actions that include the degradation of chemical compounds near the root zones and soil layers enriched with microorganisms (fungi, bacteria, etc.) that metabolize pollutants. Leaves also contribute to pollution reduction via phytoremediation, absorbing dissolved substances in water as nutrients for growth and transforming them with the help of bacteria.

Urban parks—as well as smaller spaces of scattered vegetation—act as natural water catchment basins. In addition to supporting water resource supply, they help reduce uncontrolled surface runoff [16,17]. The positive health effects related to the reduction in air pollution through urban vegetation are well established. Furthermore, the scientific community is increasingly exploring the idea that urban greening may bring broader benefits, such as reduced incidence of chronic diseases, lower stress levels, and fewer psychiatric disorders. Beyond environmental advantages, greenery contributes to human comfort in two distinct ways: first, through its shading and screening effects—providing visual comfort by reducing glare and thermal comfort through shade; second, by offering socio-psychological benefits tied to the calming effects that the presence of vegetation exerts on the human mind [18].

The performance of Nature-Based Solutions (NBS) is never uniform. In addition to climate and sun exposure, much depends on how the system is designed: including the structure’s technology and components, the irrigation and fertilization systems, and the plant species and substrate type. Contextualization and biodiversity must always be taken into account to ensure that urban greenery is long-lasting. Technologies that support NBS fall under the broader definition of Green Infrastructure and can be grouped into four main categories: tree canopy (TC), green open spaces (GOS), green roofs (GR), and vertical greening systems (VGS) [19]. Green open spaces include an integrated system of natural areas and designed spaces: flowerbeds, tree-lined avenues, gardens, vegetable plots, parks, and urban forests. Additional forms of green open space that help collect rainwater include vegetated permeable surfaces, rain gardens (shallow depressed areas), and bioswales (vegetated linear channels) [20].

These benefits (Figure 1a) are more efficient and easier to monitor in confined environments, where the limited area and reduced air volume amplify the microclimatic effects. Pocket parks, because of their small, lot-sized scale, are ideal for creating a sense of immediate environmental comfort. In these spaces, the benefits of a green environment are more perceptible.

Pocket parks are suitable for stationary use and serve as community recreational areas (Figure 1b). They act as liminal zones between public and private spaces, and their typology depends on both the dynamics that shaped the site and the needs of the community. In some cases, they may include play areas, small spaces for temporary activities, urban gardens, or simply landscaped plots to promote physical well-being and social interaction. Ideal locations for pocket parks include vacant lots, rooftops, and other underused or forgotten spaces.

In very small and elevated towns in Italy, the traditional relationship with the surrounding countryside was such that specific green design solutions were historically unnecessary; on the contrary, high density was often preferred for climatic reasons. Over time, however, urban expansion has in some cases detached historic centers from their rural surroundings, and various events have led to abandonment conditions that now require regeneration. These situations are mainly the result of progressive depopulation that has affected many minor centers, leading to general neglect and lack of maintenance of the built environment.

The historic cores of minor centers present numerous urban voids that could allow for reinterpretation. In addition, there are vacant lots with buildings in an advanced state of decay that, for economic or safety reasons, local governments often choose to demolish—generating undefined, identity-less spaces. These areas—currently paved, sun-exposed, and abandoned—could be reconceived as green spaces. Given their central location and limited size, they are well-suited to the pocket park model.

The design of pocket parks is closely linked to their urban context: the predominant use of adjacent buildings, nearby services (restaurants, commercial facilities, offices, etc.), traffic conditions, accessibility, connectivity, and the shape and scale of surrounding streets and buildings. Landscape elements may include lawns, shrubs, trees, flowerbeds, water features, seating areas, and pedestrian pathways—they are all simple interventions yet can create a small green lung in densely built environments. One of the key factors in the performance and resilience of urban greenery is the selection of plant species and planting schemes appropriate to the local climate and solar exposure. Plant characteristics influence rooting depth and width, soil type, irrigation system, maintenance needs, and water retention capacity. Specific features such as transpiration rate, leaf solar transmittance, and leaf area index directly affect thermal and acoustic performance and pollutant absorption capacity.

If green systems are technologically designed to offer local seasonal rainwater storage—known as blue-green technologies—pocket parks could achieve self-sufficiency in terms of irrigation. Rainwater harvesting is especially effective in hot and drought-prone areas such as southern Italy, where it enhances passive cooling of the environment. Blue-green technologies (e.g., permeable pavements, bioretention basins with phytoremediation, etc.) integrate water management into urban planning policies by implementing nature-based solutions to capture, store, and purify water [21].

Green and blue spaces—constructed wetlands, rain gardens, green roofs, grassed swales, and ecological parks—act as reservoirs that retain and gradually release water. The water retention function is made possible by creating a cavity beneath the soil substrate that can hold even heavy rainfall. Additionally, stored water can be recirculated through an automatic pumping system and reused for plant irrigation.

In most urban applications, tree pits are too small to allow for adequate root penetration. The soil substrates are often compacted, with low pore volume and insufficient drainage and water retention capacity. Recent approaches—such as structural soils (Figure 2a) and the Stockholm tree pit system (Figure 2b) [22]—have opened new perspectives in addressing this issue. The Stockholm system is distinguished by an integrated planter that creates a cavity within the soil bed, enabling water and air exchange for tree roots. This structure is stable and load-bearing for pavement, preventing soil compaction and root crushing. Structural soils are composed of aggregates of varying grain size (e.g., 90 to 150 mm) mixed with topsoil or biochar (a carbon-rich material derived from the thermal degradation of biomass), arranged in layers.

The untreated topsoil or biochar layer can also act as a filter to purify stormwater runoff. Structural soils are capable of supporting pedestrian or vehicular pavement loads while fostering plant growth. Soil structure refers to the arrangement of aggregates and how they compact, affecting porosity, drainage capacity, air availability, and overall soil stability. The structure must not hinder root development, allowing the plant to grow without restriction. The inclusion of adjacent aeration wells can further increase airflow and water movement toward the roots.

3. Methodology

The contribution identifies Nature-Based Solutions (NBS) as a modus operandi for the regeneration of a minor center in the Sicilian hinterland, characterized by a strong historical identity. Although the work is grounded in a case study application, both the strategy and the method are intended to be replicable in other smaller towns affected by depopulation, similar contexts—urban settings that are widespread throughout Europe.

The historic cores of such areas are often fragmented due to poor maintenance, abandonment, or various types of calamities that have created a series of voids which, if not reclaimed, fall into deep degradation. Urban greening represents a soft intervention that, beyond enhancing the aesthetic value of the urban area, can generate a better habitat in terms of thermo-hygrometric comfort, circular water resource management, and improved static response of the soil to landslide tendencies.

The case study was selected to enhance a delimited yet extensive area of significant historical and architectural value. The municipality of Naro known for its monumental Baroque and medieval architecture, is representative of a minor center in the Sicilian hinterland, marked by marginality in its province. Italian minor cities like Naro still preserve remarkable qualities that make them attractive living environments with good quality of life, and they can play a key role in the transition toward environmental policies by helping to ease pressure on metropolitan areas.

The study developed an in-depth understanding of the territory through the integration of multiple data sources and fieldwork. Meetings with the Municipal Administration, stakeholders (including associations, businesses, and neighboring administrations), and citizens proved particularly valuable. In parallel with fieldwork, research was conducted on geoportals and webGIS for urban planning, regulatory, cadastral, and restriction-related data.

The Territorial Information System (SIT) supported the processing, analysis, and visualization of spatial data concerning the urban center. To complete the dataset, urban planning tools—such as master plans, implementation plans, and sectoral plans—were also examined. Despite considerable efforts to collect information from online platforms and statistical sources (e.g., demographic and environmental data), results were insufficient. For this reason, field surveys were prioritized. These surveys allowed for the mapping of existing urban green areas, the identification and cataloging of urban voids, the assessment of historical and landscape heritage, the evaluation of building conservation status, and the analysis of prevailing land uses surrounding the identified voids. Engagement with local stakeholders further revealed a widespread demand for the rehabilitation of abandoned areas, ideally through economically sustainable solutions for the Municipality.

Understanding the nature of the identified voids required investigating urban development, the limited available historical cartography, and local geological studies.

Archeological, hydrological, and geological knowledge was acquired through a comprehensive review of scientific literature and existing cartography. Archeological studies suggest that ancient settlements were primarily located near the present-day urban core, approximately 2 km away. Within the historic center, which was the focus of the study, no significant remains have been reported aside from occasional Hellenistic finds. Supporting analyses from the municipal master plan (PRG) guided the selection of “sample areas” among the identified urban voids. As illustrated in Figure 3, areas located in high-risk zones or subject to legal restrictions were excluded.

Additional criteria also informed the selection process. Morphological features, such as slope, were used to eliminate sites unsuitable for cultivation. Environmental conditions, including solar path and prevailing wind patterns, were considered crucial in selecting appropriate Nature-Based Solutions (NBS) for solar and wind protection. Geological studies revealed the predominance of calcareous soils with a clay component, which directly influenced the choice of plant species for the project. The areas identified as urban voids are all located on public land, and the Administration has also indicated its intention to reclaim some of them. Among the understanding the nature of the identified voids, a selection was made to exemplify the various typologies found within the urban fabric. Given that the project site is located in a hot climate zone, with drought conditions and almost no shading, the urban space was found to be unlivable even for short periods of time. As shown in the map below (Figure 4), the historic urban fabric of Naro is almost entirely devoid of green areas, with the exception of a few private vegetable gardens and a single public park.

The integration of NBS into these voids aligns with a vision of urban resilience strategy and offers a solution that responds to multiple needs within the local context. The selection of NBS typologies involved an interdisciplinary approach—urbanistic and technological—in order to propose more comprehensive responses to the challenges identified during the analysis phase.

To collect and adapt potential solutions for the case study, a review of relevant case studies and best practices was conducted, with particular attention to small-scale urban gardens (pocket parks). The design process followed an iterative methodology, tailored to the specific characteristics of the urban environment, which presents significant spatial and cultural constraints. Based on these findings, intervention scenarios were formulated, and suitable NBS typologies were defined. When selecting the NBSs, fragmented or isolated urban interventions were avoided, opting instead for a systemic approach aimed at addressing resilience and biodiversity challenges at the scale of the entire town. Thus, even though each void was addressed individually, the hypotheses developed for other urban voids and the broader urban-scale objectives were consistently kept in view.

A localized technological study was essential in order to define technical solutions for integrating NBS into the identified voids, with the goal of strengthening existing risk management strategies. A constant dialog with the specific features of the built environment was indispensable, as these informed each intervention’s pathway and objectives. Additionally, the study included an assessment of plant species most suited to local climatic conditions and capable of delivering a range of co-benefits relevant to the context

4. From Urban Voids to Playgrounds and Pocket Gardens: Estonoesunsolar in Zaragoza (Spain)

The international scene was also considered in the analysis to understand which design strategies have been implemented in the presence of small-scale urban voids. The reinterpretation of urban voids as green spaces or public areas with sociocultural, environmental, and aesthetic value gained widespread traction in many urban areas in the post–World War II period, particularly in major cities across Northern Europe—such as Berlin, London, and Amsterdam—and the United States, including New York, Washington D.C., Baltimore, and Philadelphia [23].

Among the pioneers of this transformation, Aldo Van Eyck stands out in the Netherlands for his socio-educational approach to designing urban interstices awaiting redevelopment. In 1947, he created his first playground, the Bertelmanplein playground, followed by many others that would later be studied by sociologists, theorists of art and architecture, and psychologists to evaluate their impact on communities and public space [24]. These projects, including the notable Boerensteeg intervention, were characterized by the simplicity of their design: using only a few pieces of play equipment and furniture along with some tree planting, Van Eyck transformed underutilized areas of the city into intimate and functional spaces, devoted to neighborhood sociability and with special attention to childhood [25]. These interventions effectively integrated into dense residential fabrics, providing child-friendly areas and compact spaces for social exchange and community gathering [26,27].

This period marked the beginning of an intense phase of design experimentation around playgrounds, accompanied by the progressive emergence of pocket gardens and related literature. As observed by Faraci [23]: “Although limited both in scope and size, these parks represent a serious effort to improve the quality of the environment in the more crowded urban areas”. Pocket parks emerged as a meaningful response to the increasing demand for open and public spaces in Northern European cities and, later, in the United States. These interventions produced numerous examples of micro green areas embedded in the densest urban fabrics. Initially conceived as urban acupuncture operations with predominantly cultural and social purposes, they succeeded in combining intimacy with public accessibility. Today, pocket parks are integrated into broader urban systems, complementing tree-lined avenues, public gardens, and larger-scale parks. They have become key elements of wider green infrastructure networks, essential for addressing the environmental challenges posed by climate change.

Among the most emblematic examples of pocket parks is Robert Zion’s 1967 project, Paley Park in Midtown Manhattan, New York: a small square shaded by a canopy of Gleditsia triacanthos trees, enclosed on three sides by buildings and open to the street on the fourth.

These types of interventions are mostly found in contemporary urban settings and only rarely engage with the interstices of historic urban fabrics. In the latter, the prevailing tendency has been toward the reconstruction and restoration of building frontages, often overlooking the potential for designing new open spaces. Nevertheless, many urban voids still persist in both dense contemporary cities and historic urban centers, offering valuable opportunities for reinterpretation as vital breathing spaces capable of fostering social interaction—even during moments of crisis such as the COVID-19 emergency [28]. This condition reflects the needs of both temporary users—such as tourists and travelers—and long-term residents, particularly vulnerable groups like the elderly and children.

In this context, the Estonoesunsolar program, launched in 2009 in Zaragoza, stands out as an exemplary case of temporary transformation of urban voids into multifunctional green spaces. Developed by architects Grávalos and Di Monte, the initiative is notable for its ability to combine climate adaptation strategies with practices of social and environmental regeneration within the consolidated historic fabric.

Although originally conceived as a temporary reactivation program for abandoned lots, Estonoesunsolar led to the creation of a network of resilient micro-landscapes capable of counteracting local climate aridity and enhancing the city’s environmental quality. The interventions in the San Pablo neighborhood exemplify the program’s impact. The botanical garden of Calle San Blas (390 m²), for instance, served as a pilot project for the creation of new green spaces in historic areas, promoting urban biodiversity and ecological awareness through the involvement of schools and children’s associations. Similarly, the urban garden of Calle Armas (500 m²), developed with the participation of schools and senior centers, emphasized the therapeutic and community dimensions of green space, strengthening social cohesion and supporting urban farming practices. Finally, the transformation of a private lot into an urban micro-forest (280 m²) through container planting explored temporary greening methods in high-density contexts, contributing to partial carbon sequestration and mitigation of the urban heat island effect.

The Estonoesunsolar experience demonstrates how regeneration strategies for underutilized areas, even within historic centers, are not limited to restoring the functional value of abandoned spaces but also serve as tools for urban adaptation to adverse climate conditions. The integration of tactical urbanism, community-based management, and ecological connectivity fostered the development of a flexible and replicable model, capable of initiating urban transformation dynamics that, although temporary in form, left a lasting mark on the morphology and livability of public space.

Following the pandemic period, interest in pocket parks has been renewed. Thanks to their compact size and ability to fit within existing interstitial spaces, such interventions offer a potentially effective response to the growing demand for accessible green areas within short walking distances [28,29], particularly within historic urban contexts (Figure 5).

The case of Zaragoza is particularly relevant due to its climatic and morphological similarities with the Sicilian hinterland, where the case study of Naro (AG) is located. From a climatic standpoint, Zaragoza and Naro share several characteristics typical of the Mediterranean climate, marked by hot, dry summers and mild winters. However, the specific context of Sicily—with prolonged exposure to aridity and an urban fabric historically shaped to mitigate the microclimate (such as through narrow, shaded alleyways)—requires that the model be adapted to effectively meet local needs.

From a cultural standpoint, while Estonoesunsolar is in a broader urban context—where the temporary use of urban voids responds to the need to counter degradation phenomena in a medium-sized city—the application in Naro must be assessed in light of its smaller scale and its unique historical stratification. However, if Naro is considered within the broader territorial network of the province of Agrigento—recently designated as the Italian Capital of Culture—the intervention could take on strategic significance. In this perspective, the regeneration of urban voids would not be limited to a local response but could become part of a broader policy aimed at enhancing widespread heritage, contributing to the creation of an integrated system of public spaces capable of strengthening the cultural identity of the territory.

Therefore, although appropriate adaptations are needed to suit its local context, the temporary activation model for urban voids proposed in Zaragoza could serve as a meaningful reference for developing innovative design strategies in Naro, encouraging new forms of habitability and sociability within the historic urban fabric.

5. Case Study Experimentation

5.1. Naro: Territorial Context and Urban Structure Characteristics

The municipality of Naro is located in the central-southern part of Sicily and falls within the jurisdiction of the Libero Consorzio Comunale of Agrigento, from which it is 28 km away. Its territory spans an area of 20,750 hectares and features a morphologically varied landscape, with numerous flat valley zones nestled between vast plateaus. The average elevation ranges between 300 and 400 m above sea level, with some notable elevations such as Monte Pernice, which marks the northeastern border with the municipalities of Favara and Canicattì, and Pizzo Giummello, also located on the same side. On the opposite side, Monte Malvizzo rises, as well as the so-called “Castellazzo”, near the border with Camastra, where the ruins of an ancient fortified site are still visible.

The municipal territory is crossed by the Naro River, and, with a more modest flow, by the Burraito River. The latter originates from the springs in Valle Paradiso, south of the town center, and, after passing through the Serra di Furore, flows into the Naro River. Today, the waters of both rivers feed the artificial reservoirs of the San Giovanni and Furore dams, which were built between the early 1960s and the mid-1990s to ensure an adequate water supply for the entire area. In addition to their landscape value, the presence of these two artificial basins has also led to significant changes from a faunal, ecological, and environmental standpoint (Figure 6).

Compared to the coastal territories of the Agrigento area, which are more dynamic and subject to higher anthropic pressure, the municipal territory of Naro records a low population density—33.06 inhabitants per square kilometer—across a total surface area of 207.49 km². Its marginal position relative to productive flows, combined with the decline of the local economy—traditionally based on agriculture and livestock farming—and the critical state of transportation infrastructure and lack of certain essential services, are among the main factors that have led to the demographic decline of Naro. This trend reflects a broader pattern observed in many inland areas of Sicily. Indeed, the resident population has undergone a significant and relentless decrease over the past century: from a peak of 20,056 inhabitants in 1921 to just 6859 in 2024, marking a reduction of 35.2%. Conversely, since the early 2000s, the urban center of Naro has begun to host foreign residents, primarily from Romania and various African countries—most notably Gambia, Mali, and Senegal. This growing trend has brought the current number of foreign residents to 560, accounting for 8.16% of the town’s total population.

Over time, the progressive decline in human presence has generated various social costs, linked both to the physical decay of historic buildings and to the partial abandonment of agricultural land and the increased risk of hydrogeological instability. Despite these challenges, walking through the streets of Naro still allows one to perceive the remarkable architectural and spatial quality embedded in the historic city, which is characterized by a rare balance between built volumes and relational spaces, framed by exceptional natural backdrops. The urban center of Naro, whose origins predate Greek colonization as evidenced by prehistoric finds [30,31], the hinterland is dotted with archeological remains, mainly from the early Christian and Byzantine periods. The most significant of these is the vast early Christian necropolis (4th–6th century AD) that stretches along the southern tuff ridge in the districts of Donna Ligara, Coperta and Canale, about 2 km from the town center [32,33,34]. The urban center is built on a hill that rises from an elevation of 400 m at its base to 600 m at its summit. The hill features a steep escarpment on the inland-facing side and a gentler slope descending southwestward, upon which the urban fabric unfolds. This particular orography once ensured protection against enemy attacks and provided a commanding view over the surrounding territory.

Located at the highest point of the hill stand the Chiaromonte Castle and Old Cathedral, symbols of civil and religious authority. Since the 12th century, they have dominated the entire urban landscape and remain pivotal elements of the town’s structure (Figure 7) [35]. The historic center, particularly rich in architectural and artistic heritage from different eras, consists of a medieval core to which two later expansions are connected: Sant’Agostino, to the northwest, and the neighborhoods of Santa Maria di Gesù and il Lazzaretto, to the southeast. These expansions occurred between the mid-16th and mid-18th centuries [36]. The medieval defensive walls that once surrounded the oldest part of the settlement were largely demolished starting in the late 18th century. The few remaining sections were incorporated into buildings constructed along the former wall line during the 19th century [37]. Through the study of historical iconography [38], it has been possible to reconstruct the original wall layout, which defined a rhomboidal area, as well as to pinpoint the exact location of four towers and seven gates (Figure 8). Among these, the only one still standing is Porta Vecchia, located along the street of the same name.

The built fabric within the former city walls is characterized by predominantly irregularly shaped blocks of varying depth, ranging from one to three stories in height. This area contains a high concentration of religious buildings, including churches and monastic complexes, as well as aristocratic palaces of notable historical and architectural value. Within this setting, the only large-scale urban space is Piazza Garibaldi, facing the Baroque church of San Francesco. In the two sections of the urban fabric located northwest and southeast of the historic core, the blocks have a more regular, quadrangular form. In both of these areas, two major public spaces are present: Piazza Padre Favara, which faces the former monastic complex of Sant’Agostino (to the northwest), and Piazza Marconi, in front of the former monastic complex of Santa Maria di Gesù (to the southeast).

The structural matrices of the forma urbis include the system of primary roadways, such as the former Via dei Monasteri, now Via Dante, and the former Via Mercato, now Via Lucchesi [39], along which are located significant monumental residential and institutional buildings (Figure 9). The ensemble of religious buildings also constitutes one of the defining matrices of the forma urbis, functioning as a true generative and regulating system of the urban structure. Within this system, the monastic complexes of male and female orders represent the earliest forms of ante litteram collective facilities capable of providing both spiritual and material services to the community. The settlement progressively consolidated around these complexes, contributing to the definition of the urban form.

The road network of the entire historic center consists of two interconnected systems: the primary network, composed of vehicular roads, follows the contour lines of the terrain; intersecting this orthogonally is the secondary network, made up mainly of stairways and stepped paths, sometimes framed by vaulted passageways (Figure 10).

An exception is Via Lucchesi, along which stands the imposing monastic complex of San Francesco. Although this street runs parallel to other secondary routes, it differs from them in its broader section and serves as one of the main axes of the urban center. Above and below Via Dante, the sequence of architecturally significant buildings is punctuated by several stairways. Among them, the most scenic—with its majestic width and length—is the 18th-century staircase that connects the aforementioned thoroughfare to the Mother Church, overcoming a vertical drop of more than 20 m. The street network—comprising main and secondary routes, as well as access paths to residential buildings such as alleys, stairways, and stepped lanes—is closely interrelated with the system of open spaces, including squares and widened areas.

5.2. Identification of Urban Voids

Urban voids are underused or unused areas within the built environment. These spaces may arise from various causes and take different forms depending on local circumstances and social, economic, and environmental dynamics. Urban voids are a common phenomenon in growing and transforming cities and represent both a challenge and an opportunity for urban regeneration and renewal.

In some cases, particularly in the post-war era, uncontrolled urbanization processes—mainly affecting the outskirts of historic centers—also occurred within the historic core, precisely in the presence of urban voids. Urban voids thus became the pretext for continued construction in already dense areas, introducing building types that now disrupt the skyline of urban profiles of significant historical and architectural value.

Naro is a minor center whose urban fabric has, over time, been fragmented by various residual spaces—urban voids—generated by multiple phenomena. The first observation is that Naro belongs to that group of small Sicilian municipalities that, since the mid-20th century, have experienced severe demographic decline. This progressive abandonment primarily affected the built heritage, triggering widespread degradation and structural instability, leading to the collapse of parts of the building stock.

Indeed, the most frequently observed urban voids within the historic center (Figure 11 and

Table 1. Identification of the types of void in the historic center of Naro (AG).

ID	Place	Type of Void	Description	Photo
S1	Church of St. Augustine	edge void	Urban edge void with panoramic view, unmarked, poorly accessible, partially hidden by a wall
C1	Via Messina	collapse void	Site resulting from building collapse, currently leveled and improperly used as a parking area
S2	Piazza Marconi	residual	Paved and unplanned open space, considered a residual urban area, mainly used for parking and vehicle transit
F1	Via Vanelle	landslide void	Urban void caused by a landslide in 2005, now cleared of debris and partially stabilized. Enhanced through street art interventions
C2	Church of St. Anthony Abbot	collapse with remaining perimeter walls	Site resulting from collapse due to neglect, with the perimeter walls of the former religious building still standing
C3	Via Specchi	collapse void	Urban void generated by total building collapse, lacking any remaining structural elements, currently unused
S3	Vicolo Falzone	residual	Unplanned urban interstice generated by the historical urban fabric, with no defined function
S4	Piazza Gaetani	residual	Residual space near a staircase, shaped by complex urban topography, small, and currently unused

) are those resulting from the collapse of individual structures due to neglect and abandonment. These appear as empty plots where buildings have entirely disappeared or where remnants of perimeter walls are still visible. In some areas, the extent of the collapse has left buildings in near-ruin conditions, making recovery efforts prohibitively costly. In certain situations, only the perimeter walls remain; in others, the entire structure has collapsed, leaving a vacant lot. One example that preserves the footprint of the former structure is the site of the former Church of Sant’Antonio Abate, located near the Mother Church but at a lower elevation. These areas are often overgrown with spontaneous vegetation, while others have been leveled and are now improperly used as parking lots.

Other types of urban voids include residual spaces within blocks, overgrown green areas, or widened spaces on the edges of densely built zones. In addition, there are disused or poorly maintained squares, courtyards, or pedestrian areas—open spaces that were not designed and are now misused as parking lots or informal waste dumping points, turning into open-air landfills.

Some urban voids were caused by landslides that occurred from the second half of the 19th century onward. The most recent landslide in Naro occurred in 2005, affecting the southwestern section of the settlement near the castle. About 70 houses were declared uninhabitable and had to be demolished. In recent years, the area has been cleared of rubble, and the remaining wall sections have been stabilized and repurposed to support a dozen large murals.

Other voids result from neglected green areas where vegetation overgrowth prevents access, and additional small vacant areas of irregular shape can be found between buildings due to the evolving urban grid, which over time has generated unresolved interstitial spaces. Lastly, further voids are located along the urban fringe, where the built fabric is less compact or fragmented. These spots offer extraordinary panoramic viewpoints, such as the one behind the former convent of Sant’Agostino.

5.3. NBS for the Regeneration of Urban Voids

Naro represents a dense and historically stratified urban context, subject to multiple restrictions aimed at safeguarding the built heritage. One limitation concerns the placement of vegetation within urban voids, which are often bordered by the load-bearing walls of adjacent buildings. According to Article 892 of the Italian Civil Code, a minimum distance of 1.5 m must be maintained for small trees (with trunks and branches under 3 m in height), and 0.5 m for vines, hedges, shrubs, and fruit trees not exceeding 2.5 m in height. The irregular morphology of the urban fabric adds further constraints, with narrow passages, steep gradients, terraces, and ramps. These conditions strongly affect the selection of plant species and the technological systems required for their growth, stabilization, and containment. At the same time, vegetation can actively contribute to enhancing the historic urban landscape. Restoration has the potential to recover architectural and spatial qualities that are currently obscured by physical decay.

The regeneration of urban voids through their transformation into small urban parks represents a simple yet impactful intervention. Urban greening in historically dense contexts such as Naro is a compatible solution, as it does not alter the built environment—on the contrary, it enhances it. The environmental and ecological project we envisioned for the case study plays a role in stitching back together the fragmented urban fabric, both ecologically and socially. Urban greenery, in its various forms, thus becomes a public reconnection element: a place where tourists can stop to rest and where the community can come together. Nature-Based Solutions (NBS) are key tools for creating these small urban parks, allowing the city’s ecosystem services to be enhanced. Increasing urban ecosystems provides residents with resources directly from nature (such as water, timber, and food from urban gardens or orchards), natural functions that regulate the urban microclimate and control rainwater, erosion, and soil stability, along with intangible benefits tied to collective well-being.

On 4 February 2005, a ground fracture occurred in Naro’s historic center, causing structural damage to many buildings and triggering Civil Protection emergency protocols. Ground fractures, which continue to cause significant structural damage, have been known in Naro since at least 1679 and do not appear to result from landslides in the strict sense (soil disintegration). Studies have linked this phenomenon—one of the main current issues in Naro’s historic center—to the soil’s inability to retain rainwater [40]. The area’s hydro-structural condition consists of the overlap of two formations with different hydrogeological behaviors: the upper layer, composed of sandstone and shell breccia, is highly permeable and promotes infiltration of large quantities of rainwater into deeper layers; the lower layer is clayey and semi-permeable, favoring the formation of underground aquifers [41]. Rainwater from occasional and extreme events infiltrates the subsoil through the permeable sandstone layer, increasing the weight of the calcarenite blocks and the plasticity of the clays, triggering block displacements due to failure of the support surface or lateral movement.

NBSs act as natural systems that also serve as temporary reservoirs for rainwater. Certain plant species, with extensive and deep root systems, are widely used for their ability to stabilize soil. This function helps reduce the load on traditional drainage systems, promotes natural infiltration and aquifer recharge, and prevents soil erosion.

Thus, the project to convert numerous identified urban voids into new green lungs among built structures (gardens, urban gardens, tree-lined parking areas, filtering strips along roadways, rock gardens, rain gardens) also responds to the primary need of the historic center: a system that enhances the soil’s ability to retain rainwater and limits its infiltration into the subsoil. Moreover, this is a non-invasive solution that respects the historic and cultural importance of the town. Given the dense fabric of the historic center, green spaces will be small in scale, located between buildings; green corridors will run along streets, while larger areas with wetlands and agricultural greenery will be placed on the city’s edges. These green islands within the built environment will open visual corridors in the historic center, sometimes integrating existing gray infrastructure (e.g., drainage channels, embankments, retaining walls).

In the interstitial and dense urban areas not affected by hydrogeological risk, the most suitable NBS are small parks, community gardens, green relaxation or co-working spaces, orchards, and vegetable gardens. In these cases, the primary goal is to improve residents’ quality of life, especially microclimatic conditions. For this reason, plant species with high Leaf Area Density (LAD) are preferred, and due to limited space, species with compact root systems are ideal (e.g., olive, pomegranate, plumeria, birch, etc., for Sicily’s climate). Throughout the historic center, protecting pre-existing structures is imperative (including the potential to disassemble and re-lay paving), and where possible, excavation should be avoided, as vibrations could damage surrounding buildings. For this purpose, structured soils (composed of sand, silt, clay, and decomposing organic matter) may offer suitable conditions. The variation in soil particle size enhances water infiltration and retention, while organic matter acts as a binder between soil aggregates.

In some of the identified voids, nature is already gradually reclaiming space, becoming a habitat for spontaneous flora and fauna that can sometimes be preserved. In other cases, the idea is to redevelop the space with urban gardens to provide local food and promote community engagement. Many plant species thrive in Sicily’s climate, including banana, mandarin, lemon, orange trees, and various vegetables (eggplants, tomatoes, peppers, onions, artichokes, zucchinis, etc.). If the voids are near waterways, site recovery can include restoring natural water flows and implementing sustainable drainage solutions to reduce flood risk and improve water resource management. Rain gardens, bioretention areas, and tree pits are the most appropriate solutions for small-scale interventions in dense urban environments and collect runoff from adjacent areas. Naro’s historic center, like many places in Sicily, is sunny—this encourages vegetation growth and evapotranspiration of collected water. These systems should be installed at a safe distance from buildings to prevent infiltration at foundation level (thus, in narrow and confined spaces, the central area of the available space is best).

Where water infiltration into the subsoil could cause hydrogeological instability or risk contaminating the aquifer, the base of these systems can be waterproofed using geomembranes.

A rain garden (Figure 12a) is a concave green area with a single substrate layer (20–50 cm high), made of local soil mixed with compost and sand, capable of infiltrating water into the soil and purifying it through the combined action of plants, soil, and microorganisms.

Bioretention areas (Figure 12b) are small green zones situated lower than surrounding pavements and temporarily retain water, which infiltrates into the substrate and, in the case of open-bottom systems, into the subsoil, where it is filtered through vegetation and substrate.

Tree pits (or structural tree boxes) are concrete containers, with open or closed bottoms, filled with suitable substrate for tree growth and a subsurface drainage layer. These are designed to host a single tree, which may be planted in structured soils or modular systems. The Cupolex system, as in image 12c, is ideal for root management in urban areas. It prevents pavement damage and promotes healthy tree growth by creating underground spaces where roots can expand without affecting surface layers, while ensuring proper soil aeration and moisture.

Collapse voids (or landslide voids) that have created unusable or hazardous areas can be transformed to stabilize the soil, specifically through the use of stabilizing plants (e.g., grasses, shrubs, and trees with strong root systems) that help reduce erosion and prevent further landslides. This approach may involve planting native species with deep or expansive roots that bind the soil and enhance its structure. However, root systems of this type require specific technological design considerations, including the need to trench the root systems if located near built environments. Given the substrate type present in Naro, it may be appropriate to consider drainage trenches filled with permeable material, such as gravel or pebbles, which facilitate water flow and reduce the risk of waterlogging and subsidence. To prevent the clogging of the drainage material by surrounding soil, a geotextile—a non-woven fabric that acts as a filter—is typically used.

In selecting stabilizing vegetation, the main factor to consider is climate. The Sicilian climate, typically Mediterranean with hot, dry summers and mild winters, requires drought-resistant plants that tolerate intense sunlight and, in this case, have root systems capable of retaining soil on hilly terrain. Some suitable examples include herbaceous plants such as sedum, subterranean clover, and tall fescue; shrubs such as broom, rosemary, mastic, and rockrose (plants suited for arid areas and effective at holding the soil), chrysopogon zizanioides (for erosion control on steep slopes), and Mediterranean grasses. Among the trees (

Table 2. Examples of trees and bio-mats suitable for soil stabilization and the Mediterranean context.

Image	Description	Stabilization Capacity	Climatic Suitability	Fruiting Period
	Carob Tree—Large evergreen tree with broad canopy and leathery leaves.	Very high—Very deep and compacting roots.	Excellent: loves dry heat and tolerates moist soils.	Late summer–early autumn
	Olive Tree—Iconic Mediterranean evergreen with twisted trunk.	High—Excellent soil consolidation; roots adapt to soil.	Excellent: drought-tolerant, handles temperature shifts.	Late summer–early autumn
	Apricot Tree—Medium fruit tree with oval leaves and white flowers.	Medium—Expansive but with shallow roots.	Excellent: more suitable for hilly slopes and dry warm climate.	Early spring (March–April)
	Cherry Tree—Medium-sized tree with a broad canopy.	High—Very deep and well-branched roots.	Good: withstands winter cold, prefers hill terrain.	May–June
	Fig Tree—Medium-sized tree with large, lobed leaves.	High—Strong vertically growing roots.	Excellent: perfect for warm climates and sloped land.	July
	Bio-mat—Natural fiber mat held by a photodegradable mesh and cellulose layer.	Medium-high—Acts as a barrier against rain and wind.	Good: coconut or jute-based mats resist heat, decompose slowly.	–

), suitable species include holm oak or downy oak (evergreen Mediterranean oaks adapted to calcareous and hilly soils), carob, Aleppo pine, olea europaea (olive), cherry, fig, and apricot. Another solution involves the application of bio-textile materials made from natural fibers such as jute, straw, or coconut—flexible, pre-seeded mats. These biodegradable bio-mats enrich the soil and allow natural vegetation to grow, but in specific cases, they may include a synthetic mesh to increase durability and strength.

We identified NBSs (

Table 3. Models of Nature-based Solutions for small historic centers in the Mediterranean context.

ID	Goal	Proposed Intervention	NBS
NBS 1 Sustainable Regeneration in Consolidated Historic Contexts	Implement NBS in existing open spaces, interstices, and squares to improve environmental quality, accessibility, and daily usability, especially for elderly residents in dense urban centers	NBS 1.1 Multifunctional Proximity Green	Public green spaces with microclimatic, recreational, and landscape functions in densely built historic areas
		NBS 1.2 Micro-interventions in Interstices	Low-maintenance spot interventions to improve livability, CO2 sequestration, and shading in alleys and micro-urban spaces
		NBS 1.3 Rewilding of Squares and Open Spaces	Insertion of native vegetation for shading and thermal regulation in currently asphalted or impermeable areas
		NBS 1.4 Temporary and Adaptive Green Spaces	Flexible and reversible solutions for social and environmental activation of urban voids, including managed spontaneous vegetation
		NBS 1.5 Gardens of Collective Memory	Symbolic spaces integrated with ruins or remaining structural traces, with contemplative and community value
		NBS 1.6 Urban Gardens	Creation of collective gardens and educational green areas in residual spaces or urban voids, involving citizens and schools to promote local agriculture, biodiversity, and environmental education
NBS 2 Sustainable Stormwater Management	Integrate green systems for retention and slowing of rainwater in urban areas, contributing to climate resilience and soil enhancement	NBS 2.1 Permeable Green Drainage Systems	Use of permeable surfaces and integrated vegetation (e.g., rock gardens) for sustainable urban drainage (SUDS)
		NBS 2.2 Terraced Rooftop Gardens	Elevated or slope-based green solutions for water retention, increased biodiversity, and landscape enhancement
NBS 3 Ecological Soil Stabilization	Prevent soil degradation and instability through integrated green systems, improving safety and environmental quality in at-risk areas	NBS 3.1 Bioengineering Stabilization	Use of vegetation and natural systems to stabilize slopes or unstable ground, even in historic urban areas
		NBS 3.2 Multifunctional Green Terraces	Recovery or creation of vegetated terraced surfaces to reduce runoff and enhance soil value

) to achieve compatibility within a dense and highly historicized area, aiming at three macro-objectives: improving comfort (microclimatic and psycho-physical), rainwater retention, and soil stabilization. The following table concisely integrates the objectives, the proposed intervention, and the description of the suitable NBS for the stated goal. The selection of objectives and corresponding types of NBS is specific to the studied context, considering the individual urban voids identified. At the same time, it reflects an overall vision aimed at enhancing and safeguarding climate resilience and reducing the vulnerability of the historic urban center, which is affected by hydrogeological and landslide risks. Additionally, the strategy helps restore biodiversity and create opportunities to improve community well-being.

The classification follows a functional logic based on the ecosystem and social goals of the NBS, intervening transversally across the various morphological types of vacant spaces. Each specific objective can be implemented as a standalone intervention or integrated into broader strategies of climate and landscape planning and design.

In the following table (

Table 4. Identification of intervention typologies and NBSs for the regeneration of voids in the center of Naro (AG).

ID	Place	Proposed Intervention	NBS	Infographic
S1	Church of St. Augustine	Redevelopment into a panoramic viewpoint with tourist and religious value, green area and shading plants	NBS 1.1—Creation of multifunctional public green spaces with landscape, recreational and microclimatic functions
C1	Via Messina	Design of multifunctional space with green areas and rest areas to reduce summer temperatures and collect runoff due to the steep slope	NBS 2.1—Permeable soils and green infrastructure for sustainable rainwater management
S2	Piazza Marconi	Redevelopment of the square with rest and walking areas. Partial re-naturalization with greenery and reorganization of landscape and vehicle transit	NBS 1.2—Renaturalization of urban squares with vegetation for shading and microclimatic regulation
F1	Via Vanelle	Creation of a thematic linear park combining art, memory, and native vegetation for shading, identity landscape and summer cooling	NBS 1.3/2.1/3.1—Urban linear park with native vegetation for climate and landslide resilience
C2	Church of St. Anthony Abbot	Recovery of the original morphology as symbolic and educational space about lost heritage	NBS 1.5—Memory gardens and contemplative spaces with vegetation integrated into structural remains
C3	Via Specchi	Setup of temporary civic space with mobile devices and controlled spontaneous vegetation	NBS 1.4—Low-maintenance interventions with managed spontaneous vegetation and flexible, temporary solutions
S3	Vicolo Falzone	Insertion of minimal urban furniture for resting and light vegetation to foster neighborhood sociality	NBS 1.1/1.6—Proximity green spaces and micro-interventions with small urban gardens
S4	Piazza Gaetani	Redevelopment as a low-impact urban hanging garden with ecological and contemplative function, also reducing runoff	NBS 2.2/3.1—Terraced hanging garden for water retention, soil enhancement, and landscape value

), a proposed NBS intervention is assigned to a specific urban void; an infographic created by the authors aims to illustrate the concept by simulating the studied context. The choice of the NBS is strongly influenced by the analysis of the specific urban void and the various types of issues identified (social, environmental, and engineering-related). NBSs involve a set of low-impact structural and non-structural interventions that restore or create natural elements, sometimes integrating existing gray infrastructure, such as drainage channels, embankments, and retaining walls—thereby enhancing the aesthetic value of the landscape. The following examples are intended for small-scale application, within confined spaces bordered by historic built heritage, and can be considered replicable in similar and widespread contexts across the Italian territory.

6. Conclusions

In the context of minor population centers in the Mediterranean hinterland, characterized by fragmented historic urban fabrics and depopulation phenomena, the regeneration of urban voids through Nature-Based Solutions (NBS) represents a design approach to be implemented in situ. The concept of the pocket park—conceived as a “lot-sized park”—proves to be a key opportunity for dense historic centers, capable of improving microclimatic, social, and ecological benefits quickly and at low cost [11,22].

Following the implementation of several pilot cases, it would be possible to assess on site whether these interventions, tailored to the climatic and morphological specificities of the location, can contribute to:

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mitigating the urban heat island effect and improving air quality, thanks to evapotranspiration and the filtration of pollutants by vegetation;

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managing stormwater through permeable paving, rain gardens, and blue-green infrastructure systems, reducing hydrogeological risk and supporting groundwater recharge;

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strengthening social cohesion by offering spaces for rest, play, and gathering—particularly valuable for the elderly and families in dense centers;

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enhancing historical and architectural heritage by creating “gardens of memory” that interact with ruins and pre-existing structural traces.

The case study of Naro demonstrates how an organic strategy—articulated through punctual yet coordinated micro-interventions—can transform residual spaces from areas of spatial degradation into “green nodes” capable of triggering widespread urban regeneration within the built environment. The analysis of urban voids (caused by collapse, landslides, residual, or marginal) and the selection of suitable NBS (proximity green spaces, drainage systems, bioengineering stabilization) have produced a potential replicable model, capable of aligning with local development policies, national and European climate resilience measures, and the goals of the 2030 Agenda.

On the occasion of Agrigento being designated as the Italian Capital of Culture 2025—an initiative that, in addition to the provincial capital, involves neighboring minor centers—Naro could draw further momentum from the implementation of these low-impact interventions. This would offer the opportunity, on one hand, to evaluate their effectiveness against expectations, and on the other, to enhance slow tourism attractiveness and stimulate new forms of local green entrepreneurship. In the medium term, building a network of pocket parks connected to historical and scenic routes would allow:

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strengthening territorial identity by integrating cultural tourism and nature;

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attracting new residents and visitors by offering quality of life and year-round usable spaces;

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supporting the local economy by activating ultra-short supply chains for green maintenance and urban agri-food production.

Finally, the experimentation of small-scale NBS in Naro would represent a useful laboratory to refine interdisciplinary design methodologies, involving local administrations, citizens, and stakeholders. The lessons learned could guide future regeneration interventions in many minor towns across Italy and Europe, promoting a systemic approach capable of combining the protection of historic–cultural heritage with the challenges of environmental sustainability and social cohesion.