Perugia, City Walls and Green Areas: Possible Interactions Between Heritage and Public Space Restoration
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript addresses an important topic concerning the conservation and restoration of Perugia’s city walls, highlighting their historical significance and the challenges posed by degradation phenomena such as black crusts and biological colonization. The integration of architectural surveys with historical analysis and the involvement of students in the projects provide an interesting and socially relevant strategy.
The paper can be accepted for publication and the minor revision required is essentially to enhance scientific clarity, language precision, structural coherence, and methodological transparency.
Observations
Introduction
• The introduction is rich in contextual information, but lacks a clear sentence with the research question or goal statement.
• More examples in the European framework can be mentioned.
Results and Discussion
• Degradation surveys and proposed interventions are detailed, but lack quantitative data (e.g., extent of black crust cover, area affected by vegetation, structural assessment metrics).
• Figures are well integrated, but captions should be expanded to fully explain visual data without referring back to the text.
• The discussion refers to Giovanni Carbonara's theoretical framework, which is appropriate, but could be strengthened by explicit linkage to international charters or standards (e.g., SIRA, ICOMOS, Venice Charter) to situate the study globally.
Conclusions
• The conclusion section reiterates previous content without clearly stating:
• Specific outcomes from the case studies
• Limitations of the research
• Future planned activities or methodological improvements
Figures and Tables
• Figures are relevant, but figure numbers and captions require consistency. For example, ensure all subfigures are referenced in the text (e.g. Figure 4a, 4b) and all colors used in degradation mapping are explained in captions.
• No tables are included; consider adding summary tables of degradation typologies and intervention strategies to improve readability.
References
• The reference list is comprehensive and appropriate. However:
• Ensure formatting consistency, especially with journal names and italics.
• Consider adding and discuss recent international papers on stone degradation under climate change to strengthen the state-of-the-art review.
Language Style and Typos
• Several sentences are overly complex or use ambiguous constructs. For instance:
• Phrases such as “positive and picturesque phenomenon” could be reframed more objectively, avoiding subjective qualifiers.
• “A circumstance emerging also from local journalism and social media, where public perception—by both residents and visitors—has framed the spontaneous growth…”
âž” Suggest rephrasing for clarity and conciseness.
• “In a productive atmosphere of exchange of human and cultural values…” âž” Could be simplified to “In a productive environment of cultural and knowledge exchange…”
• Avoid subjective or poetic terms such as “poetic re-naturalisation” unless directly quoted from sources, and clarify when describing public perception vs. authors’ evaluations.
• Section: Abstract
Original: “it’s followed by type B and type A”
Issue: Incorrect use of “it’s” (contraction for “it is”) instead of the possessive.
Correction: “it is followed by Type B and Type A” or “…followed by Types B and A.”
• Section: Porta Eburnea
Original: “The original of the name is uncertain.”
Issue: Incorrect word choice (“original” instead of “origin”).
Correction: “The origin of the name is uncertain.”
Original: “ethereal silicate”
Issue: Likely typographical error if intended to refer to a consolidant.
Correction: “ethyl silicate.”
• Section: Restoration interventions (Porta Sant’Antonio)
Original: “desalinatedfluid mortars”
Issue: Missing space between words.
Correction: “desalinated fluid mortars.”
• Section: Porta Sant’Antonio
Original: “testifies witness to the passage…”
Issue: Redundant wording.
Correction: “bears witness to the passage…” or “testifies to the passage…”
• Section: Critical analysis
Original: “each intervention must be unique and punctual.”
Issue: Incorrect use of “punctual” (meaning “on time” in English).
Correction: “each intervention must be unique and specific.”
• Section: Parco della Cupa
Original: “out of plan mechanisms”
Issue: Incorrect technical terminology.
Correction: “out-of-plane mechanisms.”
English language is good, but an improvement can be done. In particular, some typos are found in the paper. Plese, check and correct.
Author Response
Please, find attached the point-by-point reply.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe 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 recognized as a historical heritage of high identity and cultural value. The author stated that 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 interventions strategies - coordinated between academics, students, designers and stakeholders – able to reposition the city walls as central agents of urban and cultural regeneration, rather than peripheral remnants of the past. But some problems should be improved as following.
- In the introduction, the research progress about Perugia, City Walls and Green Areas is lacking, and the author needs to offer the information. Further, the author need to analyze them.
- What is the difference between Fig.1 and Fig,3? The author should analyze them by comparison.
- In additon, what is the research meaning of this work related with Perugia, City Walls and Green Areas? And the content is missing.
- Future developments need to be improved.
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 recognized as a historical heritage of high identity and cultural value. The author stated that 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 interventions strategies - coordinated between academics, students, designers and stakeholders – able to reposition the city walls as central agents of urban and cultural regeneration, rather than peripheral remnants of the past. But some problems should be improved as following.
- In the introduction, the research progress about Perugia, City Walls and Green Areas is lacking, and the author needs to offer the information. Further, the author need to analyze them.
- What is the difference between Fig.1 and Fig,3? The author should analyze them by comparison.
- In additon, what is the research meaning of this work related with Perugia, City Walls and Green Areas? And the content is missing.
- Future developments need to be improved.
Author Response
Please, find attached the point-by-point reply.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis manuscript addresses an interesting and timely topic concerning the degradation of historic city walls and their interaction with public space and urban greenery. The paper has clear practical potential and offers valuable insights into the discussion on urban heritage conservation. However, several key elements require further development.
The introduction is decidedly too brief and does not fully meet the expectations for a scholarly paper of this type. It should be expanded to include at least four essential aspects:
- A broader theoretical context on the integration of cultural heritage with public space (currently, there is no reference to existing theories or models related to the revitalization of city walls in connection with social and ecological urban functions)
- The role of urban greenery in sustainable development policies (while this topic appears later in the article, it is not properly introduced or anchored in relevant literature)
- A review of prior studies on the degradation of historical urban structures (the paper lacks a synthesis of recent research and findings that would strengthen the justification for the study)
- Clear research aim and hypotheses (although the aim of the study is generally outlined, there are no explicitly formulated research questions or hypotheses to guide the reader through the paper)
The methodological approach is appropriate and well-executed. The integration of historical-iconographic research with on-site assessments of architectural and material degradation is well thought-out and suitable for the nature of the study. The results are compelling and potentially useful for designing conservation and revitalization interventions in historic cities.
Despite the local specificity of the topic, it would be beneficial to include even a brief comparative discussion with similar studies conducted in Italy or other parts of Europe. This would help determine whether the case of Perugia is representative or unique and would enhance the article’s relevance in an international academic context.
The authors should also include a section on study limitations.
Author Response
Please, find attached the point-by-point reply.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsManuscript number: Sustainability-3748794
Title: Perugia, City Walls and Green Areas: Possible Interactions Between Heritage and Public Space Restoration
Black crusts and biological colonization are among the most common types of ‘diseases’, with diverse etiologies and presentations, affecting masonry architectural heritage. Over the past decades, there has been an increase in the incidence of this degradation phenomena due to pollution increase and climate change, especially on th 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 recognized as a historical heritage of high identity and cultural value. The degradation reflects, in the mentioned cases, in the liminal public and green areas. A circumstance emerging also from local journalism and social media, where public perception—by both residents and visitors— has framed the spontaneous growth of herbs and medicinal shrubs within the stone joints of historic walls as a positive and picturesque phenomenon. 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 interventions strategies - coordinated between academics, students, designers and stakeholders – able to reposition the city walls as central agents of urban and cultural regeneration, rather than peripheral remnants of the past.
The article is written concisely and clearly, and summarizes the results of a substantial volume of information. The statements are correctly supported with results and explanations. I congratulate the authors on the impressive work.
I only recommend that the authors complete the article with information about:
- Please develop the state-of-the-art part, and consider also studies about the positive effect of the hydroxyapatite in the process of preventing the formation of black crusts (ex. https://doi.org/10.3390/su17135788).
- Please offer more details about the case study wall, such as detailed images, specific architectural information, decay survey (at least more pictures and some information about the spreading of the black crust on the entire wall, because the detailed part is to little to be considered relevant for the entire heritage element) or details, information about the chemical and biological properties.
- Please offer more details about the planned restoration (for example, the authors state that one step would be the preliminary filling of cracks and voids, but they didn’t say with what kind of materials would be those cracks filled; offer specific details about the proposed intervention).
- Please state clearly the opportunity for the research work and your personal contribution.
- Please state the limitations of your work.
I do recommend the paper for publication after the consideration of the major revisions because it presents important original information. But at this point, it seems too much like a student paper, so the scientific level of the paper has to be increased before its acceptance.
Author Response
Please, find attached the point-by-point reply.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe revised manuscript has solved these problems, and its present version can be published.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript has been thoroughly revised, addressing my suggestions, which has significantly improved its clarity and overall quality. The article is now much stronger in both its structure and content. Thank you for that.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors have considered all the recommendations.
Although I received the response letter for another reviewer's comments, and not for my remarks, I was able to notice in the paper that everything that I recommended was considered.
Congratulations on your work!
