The building materials of the Rocca della Verruca fortress (Tuscany- Italy)

The Rocca della Verruca fortress rises on the summit of the homonymous mountain, on the eastern side of the Pisan Mountain. It is located in a strategic position which allowed to control the whole mouth of the Arno River. The fortress remained under the Pisan influence until the 15th century, when the Florentine rule begun. After the Florentine takeover, the fortress was inspected by illustrious architects, such as Giuliano da Sangallo and Leonardo da Vinci, who planned to improve its defensive structure. It was the moment when the medieval fortress began to be modernized with the insertion of circular towers and pentagonal bastions, in the same way as the other castles conquered during the wars: the modernization of the defences was attributed to Luca del Caprina and Giuliano da Sangallo. The paper will examine the geomaterials used in the building with a particular focus on mortars and bricks studied according to mineralogical and petrographic methodologies and will verify both the variations occurred during the construction phases and the relationships with the local supply sources.