Multi-temporal Interferometric Synthetic Aperture Radar (MT-InSAR) is a widespread technique to monitor landslides and settlements of large areas. Recently, thanks to the availability of high-resolution satellite images, MT-inSAR has been also proposed to investigate the evolution of damage conditions in buildings, e.g., to identify displacement trends in crack patterns and their possible causes. However, the dataset provided by radar images can be insufficient to interpret the structural conditions, and limit the predictive aim of the method. In this work, some methodological aspects of the MT-InSAR are discussed, in view of its application to monuments and historic sites. Implementation on selected case studies pointed out that the MT-InSAR, when sufficiently validated (based on either experimental onsite monitoring or analytical and numerical modelling) can represent a useful tool to optimize tailored investigation plans and prioritize and minimize the possible interventions.