According to the latest United Nations report, 68% of the world's population will live in cities by 2050, especially in developing countries in the Global South. New challenges are emerging in urban studies, which need to move towards; The drive to develop new methodologies for analysing the sustainability and resilience of the built environment is becoming increasingly urgent, especially in the intermediate cities of southern Chile, where the latest evidence has shown that major spatial transformations have directly affected the urban lives of their inhabitants. The objectives of this study are related to: (i) evaluating the sustainability and functional states of existing buildings in a specific sector of the historic Valdivia city centre (in the capital of the Los Rios region)-specifically the Libertad pedestrian walkway; (ii) identifying key parameters for diagnosing the degree of sustainability; and (iii) proposing an intervention strategy for this specific location in one of the oldest cities in southern Chile using three fundamental design conditions: environmental, public space, and urban block. This kind of integral approach can help develop innovative procedures and improve mitigation strategies-such as preventive maintenance programmes and future control systems for maximising the resilience of a specific local context-in cultural heritage buildings, as well as in their surrounding and built environments. (c) 2021 Elsevier Masson SAS. All rights reserved.