In July 2017, the system of Bergamo City Walls was registered in the UNESCO World Heritage List, together with other Venetian fortresses in Italy, Croatia and Montenegro. This important historical document needs continuous care and caution in order to be preserved complete, despite the continuous atmospheric and anthropic attacks, giving rise to dangerous deterioration processes on the artefact. The UAV photogrammetry is a suitable surveying method for such an extended system, able to collect all the geometrical, material and deterioration information needed for an effective maintenance program, also quick enough to allow for a repeated monitoring of the entire wall circuit. This paper presents the UAV survey campaign planned, and partially already completed, in order to test the methodological choices and solve all the operational difficulties to use drones in an urban environment, mainly because short distance shooting of nearly vertical surfaces was required.

The building sector has a significant impact on the environment due to its unproductive and technologically outdated practices. Although digital tools have emerged as potential solutions, current building practices often lack automation and efficiency. Throughout history, several self-supporting techniques, i.e., construction methods dedicated to the building of shells that do not need support during the construction works, have been developed. These techniques allow for reducing waste and minimizing construction costs. Combining self-supporting techniques and digital tools could aid the development of contemporary, highly sustainable, and efficient building practices that permit the use of alternative and sustainable materials. Building on this, the research conducted defines an approach for evaluating the balanced state of masonry structures during construction works and built using robotic technologies. The approach considers the factors that govern the stability under construction derived through studying self-supporting building techniques. The proposed approach assesses the structural state under construction, evaluating the need for temporary supports. An example of a masonry arch is provided to emphasize the importance of construction factors in sustainable building practices. Then the method is applied to a real case study. Overall, integrating self-supporting techniques with digital tools has the potential to revolutionize the building sector, and create highly sustainable and efficient practices.

The historical and cultural relevance of the City Walls built by the ‘Serenissima’ Republic of Venice in the second half of 16th century was recognized in 2017 by the insertion of Bergamo, together with other Venetian Fortresses in Italy, Croatia and Montenegro, in the World Heritage List of UNESCO as transnational site. In the framework of the nomination to the WHL, the City Council together with the University of Bergamo started a campaign of studies and surveys aimed to prepare a conservation planning. The goal of this plan is to assure a constant monitoring of this artwork, so that a strict routine of controls, cleaning and small strengthening works would prevent more relevant interventions, which could corrupt the material integrity of the building.This paper delineates the methodological and operational workflow applied to the preparation of the maintenance plan, now in progress, for the Venetian City Walls of Bergamo, where the photogrammetric survey by means of UAV plays an important role. The different working phases, the adopted instrumentation, the difficulties encountered and the choices made are described, and some case studies are also illustrated that represent well the typical problems encountered for the conservation of the Walls.