Perugia, City Walls and Green Areas: Possible Interactions Between Heritage and Public Space Restoration

Abstract

Black crusts and biological colonisation are among the most common types of ‘diseases’, with diverse aetiologies and presentations, affecting masonry architectural heritage. Over the past decades, there has been an increase in the incidence of this degradation phenomena due to the increase in pollution and climate change, especially on the urban walls of ancient cities. In particular, the present research examines the state of conservation of the city walls of Perugia, which are divided into two main city walls dating back to the Etruscan and Medieval periods and are recognised as historical heritage of high identity and cultural value. The degradation reflects, in the mentioned cases, on the liminal public and green areas. A view is also reflected in local journalism and social media, where residents and visitors have framed the spontaneous growth of herbs and medicinal shrubs within the stone joints of historic walls as an apparently benign and aesthetically pleasing occurrence. This misleading interpretation, while rooted in a superficial aesthetic appreciation, nevertheless draws attention to a real and urgent issue: the pressing need for systematic maintenance and intervention strategies—coordinated between academics, students, designers and stakeholders—which are able to reposition the city walls as central agents of urban and cultural regeneration, rather than peripheral remnants of the past.

1. Introduction

The urban walls represent a complex system of historical fortifications, created primarily for defensive purposes, that delineated the original core of urban settlements. Consisting of city walls, bastions and towers defending the city gates, this architectural organism defined the physical and symbolic boundaries of the city, conditioning its morphology and urban development [1]. In the Italian context, these architectures still maintain an important identity-related role today, constituting tangible evidence of the historical and settlement evolution of urban agglomerations. In Perugia, in particular, the city walls mark a clear break between the historic centre and the modern city, acting as a constraint not only architecturally but also culturally that affects contemporary urban planning choices by limiting homogeneous and continuous building expansion. The study of this portion of Perugia’s historical heritage is therefore essential for the development of conservation and valorisation strategies, as well as for the identification of adaptive reuse solutions consistent with the needs of the community [2].

In this context, urban greenery plays an increasingly central role in sustainable development policies. Far from being a simple ornamental element, green vegetation is configured as an ecological infrastructure capable of regenerating public spaces, improving air quality and increasing the resilience of cities to climate change [3]. However, in historic centres, vegetation can also be a risk factor: if not properly managed, it can accelerate the process of the degradation of the built heritage. This gives greenery a dual value—a strategic resource for urban regeneration, but also a possible threat to conservation—that requires conscious management based on specific skills and an integrated vision. The research presented here intends to explore precisely the interaction between these two areas—historical walls and urban greenery—within a sustainable and systemic perspective. The working hypothesis is that the prudent management of vegetation, accompanied by targeted maintenance interventions, can transform the walls from neglected margins to active devices of urban and identity regeneration.

The present research focuses on three emblematic case studies of Perugia’s city walls—Porta Eburnea, Porta Sant’Antonio and the Parco della Cupa—with the objective of protecting and enhancing the city’s historical heritage while proposing a replicable intervention methodology. This approach aims at reversible and sustainable restoration interventions, recognising urban greenery and the care of public spaces as key elements for rebuilding a renewed relationship between citizenship, nature and historical memory.

The methodology adopted integrates historical and iconographic research with architectural surveys and analyses of material degradation phenomena, with a special focus on signs of accelerated deterioration and their root causes. The intention is to fully understand the dynamics at work to orient future actions in a conscious and targeted manner. In this perspective, dialogue with the municipal administration, the owner of the assets, which has already initiated numerous interventions along the city walls thanks to Art Bonus support, is fundamental. Considering the extension of the route, which stretches for about 10 km, the planning of interventions proceeds in stages, according to the economic resources available. A significant example is the restoration of the Arco dei Tei (Porta Pesa), completed in 2022. The intervention included structural restoration, the removal of infesting vegetation and the treatment of degraded materials, restoring value and visibility to an urban node of great historical importance. Also particularly relevant is the redevelopment of the Parco delle Mura, adjacent to the Parco della Cupa—one of the case studies analysed. This intervention tackled the theme of vegetation in the historical context in an integrated way, combining landscape and monumental enhancement, through the arrangement of green areas and the pedestrian path, the consolidation of the wall structures and the improvement of the area’s usability.

The Perugia cases fit into a broader national context. Among the numerous cases found in the Italian context, some exemplary interventions stand out, involving the restoration of historic city walls in conjunction with projects to enhance urban greenery, including the following:

• The Aurelian Walls in Rome (Esquilino, San Giovanni)
  Subject to several restoration initiatives aimed at enhancing the perimeter greenery and designing continuous pedestrian routes along the wall’s path. Although not yet fully completed, the project demonstrates a virtuous and integrated vision.
• The City Walls of Ferrara
  Redeveloped as a continuous linear park with pedestrian walkways, cycling paths and resting areas. The intervention is part of the city’s Green Belt and has received European recognition for its landscape and functional value.
• The City Walls of Cittadella (Padua)
  Fully restored and accessible even at height through the recovery of the patrol walkways. The project has enhanced the surrounding green areas through the controlled planting and maintenance of native tree species following sustainable principles.
  Complementary to these are notable European examples, including the following:
• The Defensive Walls of Carcassonne (France)
  A UNESCO World Heritage site, restored through a conservation-driven approach integrated with rigorous green management practices to prevent damage caused by root systems. The initiative stands out for its successful integration of landscape and tourism.
• The Historic Walls of Dubrovnik (Croatia)
  Harmoniously embedded in the coastal landscape and Mediterranean vegetation. Strict regulations ensure that the surrounding greenery remains consistent with the site’s historical identity.

Among the numerous cases previously mentioned, some stand out as in-depth studies that illustrate distinct approaches to the restoration and enhancement of historic city walls, particularly in relation to green infrastructure and public use. A notable example in the Italian context is the restoration of the walls of Lucca, which was also supported through the Art Bonus initiative [4]. This project successfully combined the conservation of fortified heritage with the needs of the contemporary city, promoting an integrated, sustainable and accessible form of public space. The walls have been transformed into a continuous elevated walkway, entirely walkable and surrounded by urban greenery. This intervention not only preserves the architectural and historical value of the fortifications but reimagines them as a landscape infrastructure—a multifunctional public asset. The approach is closely aligned with the experience of Perugia, where the Parco delle Mura has redefined the defensive perimeter as a linear green space for citizens. Both cases reflect a shared vision that seeks to reintegrate historic walls into the urban fabric through ecological, socially engaged interventions. At the European level, one of the most significant precedents is the restoration of the walls of Avignon, carried out in the second half of the 19th century by Eugène Viollet-le-Duc [5]. His work is emblematic of the stylistic restoration approach, aimed at reconstructing an idealised, unified image of the 14th-century defensive system. Viollet-le-Duc employed traditional materials such as local stone and historic mortars, while also integrating modern construction techniques to enhance durability. Nevertheless, his restoration has been the subject of substantial critical debate due to its limited historical accuracy and a tendency toward interpretative freedom. Despite this, it remains a pioneering moment in the field of heritage conservation, laying the groundwork for the recognition of city walls not only as documentary artefacts but also as spaces with renewed urban and civic significance. These experiences, in Perugia as in Lucca and Avignon, testify to growing attention being paid towards city walls, increasingly recognised as a strategic resource for the regeneration of the historic fabric. They confirm the effectiveness of integrated, multidisciplinary and participatory approaches, which involve public administrations, universities and active citizenship in a shared process of the rediscovery and enhancement of the urban heritage.

2. Historical Evolution

The topic of the urban walls of Perugia—approximately 3 km along the Etruscan section and about 7 km along the medieval stretch—warrants a dedicated study due to their historical significance and architectural richness. Some sections, currently incorporated into buildings and thus not visible (indicated in orange and light blue in Figure 1), have been either destroyed or rebuilt. A thorough analysis of these segments is beyond the scope of this work; for detailed investigations, reference is made to the research conducted by eminent scholars [6,7].

The oldest wall dates to Etruscan times, between the 4th and 3rd centuries BC. It is an imposing stereometric structure, built using large blocks of travertine and local sandstone, assembled according to a polygonal construction technique that consisted of the superimposition of freshly hewn blocks, precisely arranged to form strong and resistant walls. The Etruscan architecture, extending for about three kilometres, enclosed the acropolis of the city and included seven gateways, including Porta Marzia and Arco Etrusco. Large portions of this masonry are still visible today, often incorporated into buildings constructed in later centuries, testifying to the continuous stratification and reuse of pre-existing structures.

During the 13th and 14th centuries, in response to the increase in population and the consequent formation of new villages outside the Etruscan perimeter, a second set of medieval walls approximately five kilometres long was built. The medieval system introduced updated defensive devices such as towers and bastions. The new monumental gates of this phase include Porta San Pietro and Porta di Santa Croce [6,7]. To complete the city walls, in the 16th century, with the establishment of the rule of the Papal State, the Rocca Paolina was built at the behest of Pope Paul III: a mighty fortified citadel designed to ensure political–military control of the territory, marking the last significant phase of the defence system [8,9,10].

3. Collaborations

Perugia’s city walls are still today a fundamental element of the city’s historical landscape, although their condition is uneven. Some sections, such as the Arco Etrusco or Porta Sole, have been enhanced and are fully accessible to citizens and tourists, condensing in themselves historical memory, symbolic value and social function. Other segments, on the other hand, appear neglected, poorly integrated into the urban context and often reduced to mere retaining walls within a predominantly hilly city, thus losing their original architectural identity. The lack of an accessible narrative through guided tours and information tools compromises the understanding and appreciation of their historical and cultural value. An integrated valorisation strategy could return these architectures to centre stage, strengthening the link between urban development and historical heritage. In response to these critical issues, the Department of Civil and Environmental Engineering of the University of Perugia started a project, coordinated by the Adjunct Professor Riccardo Liberotti, in seamless cooperation with the municipal administration and involving the students on the course of Architectural Restoration and Restoration Laboratory (Academic Year 2023–2024). The relationship between the Department and the Municipality of Perugia has grown through ongoing collaboration, especially in the fields of restoration and heritage enhancement. Faculty and students have been involved in a project supported by the Art Bonus, as well as others focusing on assets not formally included in the scheme—such as the Templar Church of San Bevignate, municipally owned and studied using the same design methodology. This synergy also led to the third edition of AID Monuments, a conference organised this year with the active participation of the municipal administration and its buildings [11,12].

The projects active to-date, which are currently under crowdfunding, were made possible thanks to the support of the Art Bonus, a regulatory tool introduced by Decree Law 83/2014 and made permanent by Decree Law 106/2014. This tax mechanism promotes citizens’ participation in the recovery of public assets, offering a tax credit of 65% on liberal donations. This led to a positive model of cooperation that integrates university research, technical design and active citizenship, fostering new forms of cultural patronage (Figure 2) [13,14]. In a productive environment of cultural and knowledge exchange, the students, coordinated by the instructor, have provided the municipal administration—the owner of the heritage asset—with the results of their laboratory activities, which will be briefly presented in the following sections. In particular, the survey activities and critical analyses of the conservation status, focusing on cause–effect correlations, have facilitated the development of restoration and enhancement projects, as well as improved public awareness through publications and conferences on the importance of securing and allocating resources for their implementation [15,16].

4. Critical Analysis of Case Studies

4.1. Case Studies

The subjects of the study were two city gates representative of the different construction techniques and materials used in the two main city walls of Perugia’s historic centre: Porta Eburnea and Porta Sant’Antonio. These are two cases, along with a third to be presented later, illustrating how the material deterioration of historic architecture can impact the urban environment, fostering neglect and vicious cycles at cultural and social levels (highlighted with the green box in Figure 3).

The deterioration of historical stone-built heritage presents, indeed, a significant conservation challenge, requiring a comprehensive approach that considers building materials, preventive measures, restoration strategies and adaptation methodologies. Understanding the decay processes affecting stone heritage and predicting future risks to its preservation are closely linked to the properties of the materials and their responses to the emerging environmental stresses, strongly influenced by pollution and climate change effects. However, a fundamental distinction is made in both the case studies: even before restoration interventions, there are critical issues related to the mere management and maintenance of the heritage, which cannot be overlooked. The results underline the urgency of planned maintenance and restoration management, capable of transforming the city walls from marginalised elements to protagonists of urban and cultural regeneration [17,18,19].

4.1.1. Porta Eburnea

Porta Eburnea, belonging to the Etruscan wall, was analysed by students Alessandro Antonelli, Sara Fossatelli, Raffaella Ottuso and Giulia Stefanetti (Figure 4a,b). Situated at the top of a slope and characterised by a particularly narrow passage, the gate was difficult to access and therefore naturally defended. It still preserves original travertine ashlars up to the impost of the roof, which was replaced in the 14th century by a medieval pointed arch. The origin of the name is uncertain: it could derive either from the “almond” shape of the arch, or from the Latin word “ebur”, alluding to the ivory of the elephant’s tusks, the symbol of the district. The only surviving decorative element is a lion’s head in travertine, flanked by letters that are believed to compose the inscription “AUGUSTA PERUSIA—COLONIA VIBIA”, also found on other Etruscan gates, such as the Arco Etrusco and Porta Marzia [20].

From a structural point of view, the gate does not present any serious injuries, but does show some missing ashlars due to the deterioration of the mortar connections. The main factors of deterioration, such as colour alteration, are weathering (e.g., rain, freeze–thaw cycles), as well as the growth of spontaneous weeds. Internally and externally, black crusts are evident, concentrated mainly on the extrados of the arch, caused by smog produced by vehicular traffic, as the door is vehicular, and by climatic changes that accelerate deterioration (Figure 5) [21,22].

The planned restoration intervention mainly consists of the following operational phases:

• Preliminary dry cleaning using brushes, spatulas and vacuum cleaners aimed at removing surface deposits, guano, etc.;
• Disinfection with nitrogen organic compound biocide applied in two coats, with the second application 7–10 days after the first;
• Localised biocide treatment on areas with the most aggressive biological colonisation;
• Preliminary filling of cracks and voids by means of the filler (powder of material consistent with the pre-existing one) and the pouring of mortar as a binder;
• Re-adhesion of flakes on travertine surfaces;
• Cleaning with a low-pressure, non-aggressive, deionized-hot-water pressure washer with a high solvent action;
• Chemical–physical cleaning in areas affected by detrital crusts and extensive patinas with a poultice based on AB57 liquid cleaning solution mixed with a supporting product;
• Final chromatic retouching;
• Mechanical dry cleaning with precision tools such as the sorghum brush;
• Removal of cement-based filler followed by macroscopic filling;
• Integration of missing parts, with or without stainless steel pins;
• Final disinfestation treatment using slow-release biocides to prevent the development of micro- and/or macroflora;
• Final chromatic revision.

To complete the intervention, recent scientific studies have highlighted the crucial role of environmental factors—in particular humidity, temperature and pollution—in the proliferation of the microorganisms responsible for the deterioration of stone materials. In this context, hydroxyapatite (HAp), a calcium phosphate compatible with the natural constituents of stone, has been the subject of promising experiments as a protective and consolidating treatment. Tests on historic buildings, including the Banloc Castle in Romania, have shown that the use of mortars containing 20 percent HAp improves weathering resistance and limits the formation of black crusts, without compromising the aesthetic appearance of the surfaces [23,24]. Although this technology has not been applied in the specific case of Porta Eburnea, it constitutes an interesting reference to evaluate in view of future restorations along the Perugian walls, also in consideration of the opportunities offered by the Art Bonus and with a view to a sustainable, reversible and prevention-oriented restoration.

4.1.2. Porta Sant’Antonio

Porta Sant’Antonio, located along the medieval city wall of Porta Sole on the northern side of the city, was built in 1374 at the behest of Abbot Monmaggiore using a design by Matteo di Gattapone (Figure 6a,b). Destroyed by the Perugini in 1424, it was rebuilt in brick in 1519 to defend against attacks by the Duke of Urbino. The plaque above the arch testifies to the passage of the Bersaglieri troops in 1859, an event that gave the current name to the street, once called Via Sant’Antonio. The gateway retains evident masonry traces of subsequent transformations, especially on the outer side [25,26,27].

Students Alessia Amadei, Letizia Busani, Benedetta Romualdi and Engineer Federico Aprile detected an advanced state of degradation linked to environmental exposure and vehicular traffic, which has accelerated the formation of black crusts, biological patinas and disintegration. The sandstone parts, thanks to the properties of the material and recent cleaning operations, are better preserved than those in limestone, which are more subject to biological aggression and colour changes due to pollutants. Here too, weeds threaten the physical and mechanical characteristics of the stone blocks (Figure 7) [28,29,30,31].

The planned restoration intervention mainly consists of the following operational phases:

• Dry mechanical removal of loose surface deposits using soft brushes and natural fibre brooms;
• Preventive adhesion of any materials at risk of detachment, consistent with the pre-existing limestone;
• Localised pre-consolidation by brush application of ethyl silicate to increase the surface cohesion of the stone materials;
• Pre-consolidation by injections of desalinated lime-based fluid mortars for filling or stabilising detached areas;
• Remediation interventions on cavities, metal flashings and metallic elements;
• Inspection of all existing mortar/cement fillings and overlays, with mechanical removal or reduction as needed;
• Disinfestation of invasive vegetation through the application of nitrogen organic herbicides and the mechanical dry removal of residues with wooden spatulas;
• Cleaning of incoherent deposits and greyed areas;
• Consolidation and integrations: micro-stitching of stone and elements and filling and micro-filling with brick consistent with the pre-existing brick to provide support to the upper stone elements;
• Construction of a lime mortar cresting “cap” on the top of the wall;
• Surface protection through the application of an organic protective material to obtain a water-repellent but vapour-permeable surface, obtaining the final aesthetic presentation.

4.1.3. Critical Analysis

In both cases analysed, the methodological approach included a rigorous historical analysis, a detailed architectural survey and a systematic mapping of material pathologies. The main forms of degradation identified—such as black crust, biological patinas and material disintegration—require specific interventions that go beyond superficial cleaning or structural consolidation. It is essential to identify and address the underlying causes of these phenomena to prevent their recurrence over time. Consequently, proposed interventions must be based on the principles of reversibility, compatibility and respect for both the original material and the symbolic and identity-related value of the architecture. The case studies represent a replicable methodological model for understanding and addressing the principal degradation processes affecting historic architecture. The proposed design solutions, integrated with historical–iconographic research and diagnostic investigations, aim at defining a restoration model that is conscious, calibrated and contextually responsive, grounded in a critical and multidisciplinary vision of intervention.

This approach finds a solid theoretical reference in the thought of Giovanni Carbonara, a key figure in post-war Italian restoration theory and founder of the so-called Roman School. Carbonara defined restoration as “an act of critical culture”, a scientific and philological practice based on a correct historical interpretation [32,33]. He rejected stylistic reconstruction and emphasised the importance of distinguishing between the causes and effects of degradation, arguing that interventions should target the underlying mechanisms, not merely their visible outcomes.

To reinforce the methodological and theoretical soundness of this framework, it is essential to contextualise Carbonara’s thinking within the broader international charters and standards that define contemporary conservation ethics. The Venice Charter (1964), a foundational document of the International Council on Monuments and Sites (ICOMOS), outlines the key principles of modern restoration, including respect for historical authenticity, legibility of interventions, material compatibility and reversibility [34]. These principles are fully aligned with Carbonara’s approach and are reflected in the operational methodology adopted in the case studies. Further alignment is found with subsequent ICOMOS documents, such as the Principles for the Analysis, Conservation and Structural Restoration of Architectural Heritage (2003), which stress the importance of interdisciplinary work, historical and scientific understanding and integrated diagnostic approaches [35]. Nationally, the SIRA (Società Italiana per il Restauro dell’Architettura) provides guiding criteria for Italian practitioners, promoting restoration as a cultural and scientific act that integrates historical–critical, technical and design perspectives [36]. The integration of these normative frameworks with Carbonara’s theory allows for the development of a robust, internationally recognisable operational model capable of reconciling local identity with global standards of conservation. Within this framework, restoration is not merely a technical act of preservation, but a critically engaged and culturally responsible practice aimed at safeguarding the material and intangible memory of historic architecture through carefully calibrated, site-specific interventions that respect its temporal stratification.

4.2. Parco della Cupa

This study also covered large, neglected and in an advanced state of decay sections of Perugia’s city wall, which extends for approximately eight kilometres. In particular, the research coordinated focused on the south-western area at the foot of the acropolis, near the Parco della Cupa and the street of the same name (Figure 8). The analysed section, belonging to the Etruscan wall, consists of travertine blocks arranged according to polygonal or pseudo-isodomic techniques. Currently, this segment of the wall is in a critical condition that compromises not only its structural integrity, but also the usability of the adjacent amphitheatre designed by landscape architect Pietro Porcinai (Figure 9b), unlike the Parco delle Mura, which has already benefited from a restoration intervention through the Art Bonus, allowing for an improvement in its urban greenery and making it currently accessible (Figure 9a).

Although punctual interventions have been carried out in the past (e.g., the installation of support structures by engineer Sisto Mastrodicasa, Figure 10b), the area is currently marginalised and lacks a strategic vision. A site of considerable historical and landscape potential has progressively fallen into neglect and decay, resulting in the interruption of public access and an increase in vandalism. This case is emblematic of the consequences of inadequate architectural maintenance, which can disrupt the continuity of both urban and cultural development. Within this context of abandonment, nature has gradually reclaimed the space: spontaneous and invasive vegetation has colonised the wall surfaces, further encouraged by the inefficiency of drainage systems (Figure 10a). The combined action of moisture and atmospheric agents has accelerated the physiological ageing of the stone blocks, compromising their structural stability [37,38]. Such environmental conditions also contribute to the onset of additional deterioration phenomena, such as the formation of black crusts, which are particularly prevalent on calcareous stone surfaces, as found in this section of the wall. The penetration of roots, microorganisms and lichens has triggered deep disintegration processes, accompanied by the appearance of salt efflorescence caused by harmful chemical reactions [39,40,41]. Paradoxically, this degradation has at times been described by some media as a fascinating return of nature, attributing a positive value to the vegetation creeping between the stones (Figure 11a,b). However, this evocative interpretation reflects an aesthetic and superficial perception that does not align with the authors’ technical assessment: what may seem like a harmonious fusion between architecture and the natural environment is in fact a tangible sign of neglect. In this context, vegetal growth does not enrich the site but contributes to its deterioration, infiltrating cracks, fracturing blocks and compromising the material unity of the structure. The situation emblematically highlights the difference between maintenance and restoration: while the former implies constant and preventive action, aimed at conservation over time, the latter intervenes in already damaged assets, with complex and invasive operations. Timely maintenance (e.g., by replacing the water disposal system) could have prevented the onset of advanced degradation phenomena such as the proliferation of vegetation and the biological patina. Considering what has been observed, it seems imperative to promote greater awareness, both in institutions and the public, of the importance of planned maintenance. Talking, documenting and analysing are not marginal activities, but fundamental tools for prevention. And prevention, in the field of conservation, represents the most effective and sustainable form of protection [42].

5. Conclusions and Future Developments

Starting from the lived experiences and perceptions of citizens and visitors who interact daily with Perugia’s historic walls, a diffuse and identitary architectural heritage, this work explored the potential of participatory restoration paths, promoting a solid framework of collaboration between academics, planners and public administrators. This synergy favours the co-creation of effective intervention strategies, capable of consciously addressing the challenges of urban conservation, giving rise to scalable and adaptable methodologies oriented towards the sharing of knowledge and resources, the planning of targeted actions and the reintegration of historical architecture into the life of the city. This initiative also took on strong educational value, offering authors and students the opportunity to deal directly with heritage through surveys, analysis and design, in constant dialogue with the community and local authorities. The operational limitations that emerged—from the scarcity of economic resources and the complexity of management to the ambiguity in the perception of spontaneous greenery—were interpreted not as obstacles, but as opportunities for reflection to perfect the operational model. The need emerged to strengthen a shared culture of care and maintenance through dissemination tools, participatory paths and coordinated preventive management. In this perspective, the experience conducted is configured as a replicable model, capable of combining protection, use and active participation.

Thanks to the participatory and multidisciplinary method adopted, both case studies—Porta Eburnea and Porta Sant’Antonio—are now the subject of restoration works financed through the Art Bonus, demonstrating the validity of the applied approach. These two projects, currently in the development phase, represent a concrete starting point for the extension of the project to the Parco della Cupa, configuring itself as research “in progress”. It is in this perspective that the Parco della Cupa assumes a strategic role: despite the criticalities that have emerged—the uncontrolled growth of vegetation on the wall face—the area is still excluded from any restoration project. The experience gained from the case studies can therefore be used to raise awareness of the need to include this stretch in the process of urban heritage enhancement and regeneration [43,44,45]. In response to these urgent needs, the restoration of the Parco della Cupa’s walls is proposed as an integral part of a broader redevelopment project, which includes the removal of weeds and the creation of an efficient rainwater management system, as well as the insertion of a pedestrian path and furnishings consistent with the landscape—in continuity with what has already been experimented with in the adjacent Parco delle Mura—to restore usability to this stretch of urban green space, enhancing its potential and reinforcing the connection between spaces. The project for the Parco della Cupa is configured as an open master plan, a future strategic design that can be progressively implemented as soon as the necessary funding is found [46,47].

This design strategy makes it possible to reintegrate historical walls into the contemporary urban fabric, balancing environmental needs and cultural values. Architectures, thus reactivated, assume a central role in urban regeneration processes, transforming themselves from neglected margins into vital elements for the city [48,49,50]. The case studies, still in evolution, are proposed as an open laboratory where research, design and participation intertwine to outline a more inclusive and aware vision of urban space, capable of recognising and enhancing the authentic meaning of the historical heritage. Each intervention thus becomes an opportunity for not only the physical, but also cultural and civil regeneration of the city.