Sustainable Third Places in Historic Urban Landscapes: Multi-Dimensional Assessment of Nakhon Si Thammarat, Thailand

Historic urban landscapes (HULs) represent complex environments where contemporary daily life interacts with living heritage. This study focuses on “third places,” informal social spaces outside home and work, as critical infrastructure for urban resilience. Addressing the lack of multidimensional assessments in Southeast Asian heritage contexts, this study develops and applies a context-sensitive assessment framework that integrates the HUL approach with four sustainability pillars: physical, environmental, socio-cultural, and governance–economic. Nakhon Si Thammarat was selected as a representative case study of a multicultural living heritage town where Buddhist, Muslim, and Chinese cultural layers uniquely converge within its urban fabric. Through field surveys and spatial mapping, 17 sites were empirically identified based on Oldenburg’s characteristics and evaluated via a structured rubric. Findings reveal a significant systemic imbalance: while the socio-cultural dimension is highly sustainable (M = 2.44), driven by robust cultural diversity, the environmental (M = 1.03) and governance–economic (M = 1.38) dimensions are considerably weaker. Key deficiencies include poor low-carbon accessibility and limited community participation. Notably, religious courtyards emerged as effective “living heritage” prototypes (M = 2.04), bridging sacred and secular functions. The study suggests that historic urban management should prioritize micro-scale environmental retrofitting and co-management models, leveraging existing social capital rather than wholesale urban restructuring. This flexible framework is transferable to other multicultural historic towns in the region with comparable contextual conditions.