Castelvecchio, originally called Castello di San Martino in Aquaro, is a castle in Verona currently used to house the civic museum, it is the most important military monument of the Scaligera family. The new castle was pruned between the head of the town on the right of Adige, near the Upper Chain, and the head of the town on the left of Adige, near the Porta San Giorgio. The functional and architectural essence of its position is that of constituting an element of urban defense inseparable from the river, and at the same time predisposed to project its action beyond the river itself. The bridge, for the exclusive use of the castle, served as an escape or access route for aid coming from the Valle dell'Adige, thus preventing the river from becoming an insurmountable barrier. But within the complex urban defensive system it could be used to organize sorties in order to operate tactically on the opposite river banks. The castle was designed as the fulcrum of the entire defense system, and its main tower as the center of the visual control of the city, on the left and right of Adige, and the surrounding landscape. The complex layout of the castle is generated by several construction phases, transformations and restorations over time. Today there are three parts, the so-called Court of the Scaligera Palace, to the south, the Court of Arms, in the north, separated by the Court of the Mastio, today very transformed, on multiple altimetric levels, after the late nineteenth-century rectification of the access to the fortified bridge.
Between the Court of the Keep and the Court of Arms stands the high wall embattled, imposing rest of the walls sull'Adigetto, of the communal era, existing in the castle. The curtain extends from the Clock Tower to the bank of the Adige, near the bridge. They signal successive constructive phases, and reconstructions, the different wall textures and the different materials in work: at the extremities the wall is made of rough blocks of tufa, remainder of the original construction (first half of the XII century); in the central part, rebuilt after the collapse of 1239, the wall is in alternating bands of pebbles and bricks. Toward the Clock Tower there is a stretch of large stone blocks, recovered from ancient buildings. The original Clock Tower, demolished by the French of the general Napoleon Bonaparte, rose in a more prominent position on the course, almost in contact and in defense of the Arco dei Gavi, incorporated into the municipal walls of the Adigetto and transformed into an urban gate.