**5. Discussion**

In recent years, research has begun to focus on historic districts in cities, and quantitative studies can accurately determine the problems in the spatial development process of the districts and remedy the current situation that heritage planning projects ignore the relationship between the local and the whole. Koohsari used the historic district of Taiping Street in Changsha, China, as an example, compared the cognitive map and the syntactic model, and found that the syntactic model and the cognitive map's nodes had a strong correlation, as well as the road networks [39]. Using axial and image maps, Yu and Liu investigated a specific variation of Gulangyu Island in Xiamen, China [40]. Kubat investigated pedestrian and vehicular activities in Sharjah historic center in the United Arab Emirates (UAE) to comprehend the existing movement patterns and examine the physical structure [41]. Wang and Bramwell compared historical urban districts in China using a space syntax [42]. Previous research results have focused on comparing and analyzing the relationship between space syntax and cognition to provide a basis for the design process. In this study, we use the integration, connectivity, control value, depth value, and intelligibility of space syntax theory to dissect the spatial cognition of the Sishengci historic district, not only to analyze the spatial structure but also to propose the conservation strategy of the historic district as a result, which provides a new perspective for the study of strategic conservation of the historic district.

In this study, some insights can be drawn from the case of the Sishengci historic district in the conservation and development of historic districts. Quantitative analysis should be integrated into the whole dynamic process of district conservation and development. The conservation of historic districts is a dynamic process. Urban problems will arise if the focus is only on the material heritage, such as historic buildings and historical relics, ignoring the social logic of space formation. It is necessary to comprehensively balance various factors, such as people's life, historical carriers, and newly implanted functions, and quantitative analysis and simulation integrated into the process of district conservation can maximize the conservation of the spatial structure and material carriers of historic districts. For example, in the stage of historic district conservation planning, quantitative analysis by space syntax is used to investigate, analyze the spatial structure of the district, and delineate the core conservation area of the district, which can maximize the conservation of the physical environment and social structure of the district.

#### **6. Conclusions**

Conservation of the historic districts' space is an important way for cities to inherit history and continue their cultural lineage. The formation of the historic district is influenced by various factors, such as natural conditions and social development, and its spatial form has shown its inherent development law in the development process. This study analyzes the space of the Sishengci historic district based on the space syntax, aiming to study the spatial form of the conservation and development strategy of the Sishengci historic district from a new perspective. The overall space and street space of the historic district are interpreted through the space syntax, analyzed in terms of integration, connectivity, control value, depth value, and intelligibility, and the conservation strategies are proposed in a targeted manner: emphasizing the focus on conserving the core area in the whole, refining the cultural genes of the historic district in the spirit, and emphasizing the street space interaction function in the social attributes, all of which have a guiding significance for the conservation and renewal of the space of the Sishengci historic district.

The analysis of the morphology of the historic district through the space syntax and the exploration of targeted development strategies are conducive to the inheritance of historical culture, regional characteristics, and the development of spatial morphology. At the same time, it is also conducive to the conservation and continuation of the spatial configuration of the historic district from a long-term perspective and the systematic conservation and development from a sustainable development perspective. Historic districts rich in cultural connotation and place memory not only promote the creation of urban image and cultural value but also satisfy people's pursuit of culture and spiritual enjoyment in the future, which has important strategic significance for the development of historic district space in Chengdu.

**Author Contributions:** Conceptualization, W.L.; writing—original draft preparation, W.L.; supervision, Y.A. and H.H.B.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data is contained within the article.

**Acknowledgments:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
