STREMAH 2021 is the 17th International Conference on Studies, Repairs and Maintenance of Heritage Architecture. The meeting has taken place on a regular basis since the first conference started in Florence (1989). he importance of retaining the built cultural heritage cannot be overstated. Rapid development and inappropriate conservation techniques are threatening many heritage unique sites in different parts of the world. This conference aims to provide the knowledge required to formulate regulatory policies, to ensure effective ways of preserving the architectural heritage. The series has been most successful and the conference continues to attract a wide range of high-quality contributions since it started in 1989. The meeting addresses a series of topics related to the historical aspects and the reuse of heritage buildings, as well as technical issues on the structural integrity of different types of buildings, such as those constructed with materials as varied as iron and steel, concrete, masonry, wood or earth. Restoration processes require the appropriate characterisation of those materials, the modes of construction and the structural behaviour of the building. This knowledge can be gained through a series of material characterisation techniques, preferably via non-destructive tests. Modern computer simulation can provide accurate results demonstrating the stress state of the building and possible failure mechanisms affecting its stability.