La ‘fortezza veneziana’ di Bergamo: studi per la mappatura speditiva di 5 km di mura, parte integrante del paesaggio cittadino

The ‘Venetian Fortress’ of Bergamo is a very well-known example of integration of a strong military defensive apparatus in the urban landscape of a living city. The particular configuration of the town, growing over a hill and near the feet of the Alps, make this workmanship particularly impressive. From the moment of his construction in XVI century, by the wishes of the Republic of Venice, the great fortification of Bergamo was never attacked; but it created a strong separation between the ‘upper town’, closed in the fortress, and the ‘down town’, that was already developed around the roads connecting the surroundings. This situation definitely conditioned the development of the town along the centuries, but finally allowed not only the survival but also the embodying of the fortress in the town, thanks to a constant care and a peaceful reuse of the military architecture as panoramic promenade and green belt. In the framework of the continuous maintenance project set up by the City Council, funded by Fondazione Cariplo, and the UNESCO 2016 nomination ‘Opere di difesa veneziane tra il XVI ed il XVII secolo’, supported by MiBACT, a specific project was set up in order to survey and control the whole extension of the city walls: more than 5,000 m long, for a wall surface of around 70,000 m2. The automatic three-dimensional survey – with both active (laser scanning) and passive sensors (terrestrial and aerial photogrammetry with drones) – offers new opportunities for metric and material monitoring of landscape and historic buildings. The quick acquisition of spatial geometries, combined with a high metric and chromatic reliability, allows an easy planning of the survey campaigns. If scheduled on a regular and cyclical basis, they can help to build a powerful database documenting the overall situation. Since summer 2015, a first trial on the complex of the former church and convent of Sant’Agostino and the surrounding walls has been developed. Fifteen flights lasting an average of ten minutes were carried out in the closed system of the University campus and the city park of Sant’Agostino. The survey carried out simultaneously on the ramparts and on the complex, usually studied separately, gave the opportunity of unusual observations at the environmental scale. The results obtained are encouraging in terms of the richness and usability of gathered information.