This paper studies the Xi’an City Wall (XCW) as a sustainable historical heritage. Based on the conservation process of XCW, the study is focused on four experiences that drive its sustainable development. First, the opening of gates through XCW helped to maximize its preservation while meeting the needs for urban transportation. Second, transforming XCW into an urban public space facilitated the gradual building of its camp into a city-dominated landscape. Furthermore, integrating social activities into the public space carried by XCW brought people closer to the heritage. Moreover, the use of XCW as the benchmark for the modern Xi’an urban space pattern ensured the continuation of its historical coordinates on the basis. In order to maintain the sustainability of XCW, a future sustainable development plan is put forward according to the Historic Urban Landscape (HUL) approach proposed by UNESCO. This plan has a generalization guiding significance for the future policy formulation of XCW. Findings from this study serve as a reference for the planning and conservation of historical heritage in cities.

Aiming at the problem of difficult data collection and modeling in high-rise ancient buildings with narrow interiors, a method is proposed in this paper for modeling and supporting digital restoration based on unmanned aerial vehicle oblique photogrammetry combined with three-dimensional (3D) laser scanning technology. The ancient watchtower complex in the Tibetan region of China is taken as an example. Firstly, the data is collected using an unmanned aerial vehicle and 3D laser scanner. Secondly, the two types of data are merged to generate a three-dimensional status model. Finally, by analyzing the status model and combining the similar remaining conditions, a virtual restoration scheme is proposed, and a 3D restoration model is established. The results show that virtual restoration based on 3D measurement technology can be used as a new method for the research and protection of towering ancient buildings, asrecorded by adopting targeted technology for digital documentation. It is necessary and effective to adopt a method combining unmanned aerial vehicle oblique photogrammetry and the ground 3D laser scanning technology in harsh environments. The digital model can promote the sustainable utilization of cultural heritage. It is necessary to analyze and make full use of the status model of such ancient buildings based on accurately measured data for the virtual restoration of the damaged ancient buildings. The status model of the ancient buildings can be used for display browsing and disaster recording. The restoration model can be dismantled and used to guide the repair work.

With rapid urbanization, contradictions between rapid economic development and a lack of spiritual culture become increasingly complicated. Accessibility is a useful spatial quantitative index to evaluate the spiritual and cultural construction of the city. Amongst various accessibility methods, the two-step floating catchment area (2SFCA) method is suitable for evaluating cultural urban land use (CULU) based on its advantage of flexibility and rationality. This study selects Xi'an as the representative ancient city. Based on comparing accessibility results between different travel modes (walk, bus, subway, and total), and analyzing through statistics, Z-score, and comparison of classification, comparison of a particular area, we obtain the characteristics of CULU accessibility in Xi'an. Firstly, for different travel modes, the distribution of CULU accessibility value in Xi'an is imbalanced, and the accessibility value of bus and subway is closely related to public transport resources. Secondly, CULU in Xi'an has apparent features of being dense in the center, sparse in the suburbs, and lack edge, which correspond to the development of the city. Finally, about 60% accessibility value is contributed by historical CULU, which reflects the typical characteristics of Xi'an as an ancient city with rich historical resources. This study profoundly analyses the attributes of CULU in Xi'an and provides essential data for decision-makers. Furthermore, it gives a significant exploration for building a CULU evaluation system in the future.

Historical sites generally contain cultural and natural elements and contribute to the charm of a city. Their development can also help shape urban branding and boost economic growth. Therefore, this study selects two representative pagoda courtyards in the ancient capital Xi’an to investigate how historical sites can benefit more people. Both of the pagoda courtyards are outstanding cityscapes since they were erected in the Tang Dynasty. They have been continually repaired and maintained by later generations, and the surrounding environment design of the courtyards is organically integrated with the urban structure of the past dynasties. In the wave of urban construction in recent years, the two pagoda courtyards are also facing different environmental design paths. However, both scholars and the public are concerned that large-scale space development will damage the psychological perception of historical sites. The Perceived Restorative Scale (PRS) was adopted to study the courtyards' mental restorativeness. Through semi-structured interviews and thematic analyses, the diverse sources of mental restoration are demonstrated. Overall, PRS results verify the mental restorativeness of the historic pagoda courtyards. Furthermore, the pagodas' varied modern urban designs manifested different restorative perceptions for individuals. This study provides pre-development data for the SW regarding its spatial perception. Secondly, this study provides a scientific basis for urban planning and management strategy, adding to the debate surrounding conservation and utilisation of urban historical/cultural environments. It informs open design principles for the regeneration of historical/cultural environments in the urban fabric.

Investigating the mathematical and geometric principles embedded in ancient classic architecture is a significant tradition in the history of architectural development. Drawing inspiration from the modular design and creative ideology based on the geometric proportions of squareness and roundness in ancient Chinese architecture, we propose a new mode of squareness and roundness composition based on scale proportion specifically for the design of multi-story buildings. Taking Yingxian Wooden Pagoda as the case study, we not only re-evaluate the modular system and proportional rules followed in the design of the entire pagoda, but also reveal the technical approaches and geometric rules for effectively controlling the form of multi-story buildings. In particular, the mode of squareness and roundness composition based on scale proportion, utilizing a modular grid combined with squareness and roundness drawings as decision-making tools, can control the scale and proportion of buildings across different design dimensions and organically coordinate the design of multi-story buildings’ plans and elevations. Thus, it can achieve an effective balance of multi-story architectural forms. This study has potential applications in the creation of traditional multi-story buildings and heritage restoration projects, and offers valuable insights for future research on ancient multi-story buildings.