Survey methods for the heritage and vulnerability values in a block of mexico city historic centre

This paper constitutes an updated report of the work carried out on the urban block of the historic center of Mexico City, in particular the urban survey of a block between the Plaza Major and the archaeological site of the Templo Major, a site arranged where it once stood, up to the Spanish conquest, the ancient Aztec capital of Tenochtitlan, built over the Texcoco lake with piling structures. The paper analyzes the opportunities offered by integrated digital surveys, made with different methodologies, mainly 3D laser scanners and photographic shots with SFM processing, for documentation and diagnostics aimed mainly at the conservation and restoration of architectures. At the urban scale, the survey focuses on the documentation of the urban facades and pays particular attention to the analysis of the plastic deformations and of the masonry walls, in order to evaluate the misalignment value of the fronts of the buildings from the vertical plane and the interactions between the walls of different building units. Going down from the scale of detail to the architectural detail, the restitution and analysis of individual building units was also studied, closely linked to the asset value of the area; attention was focused on the survey for the documentation, the analysis of the state of structural conservation, reaching as far as the identification and classification of the lesions, the verification of the main failures of the structures and any states of risk of collapse.