At the beginning, the fortified system of the Borgo was limited to the fort and the plateau around Conte Rosso Square (corresponding to castrum romanico). In the following centuries, mainly due to the strong influence of Savoy Castle, people began to build more and more around the fortified cliff instead of scattering around the territory. New suburb hamlets were born, gradually enclosed and protected by successive concentric layers of fortified walls.
Of the remains, decorative elements can still be seen, such as the door of Via XX Settembre, the tower along Via Porta Ferrata with its suspended arch mouldings in relief, its modillions and bands with bricks placed in a saw-edge design and mouldings with various design, and the guard tower, now annexed to a private property.
On the opposite side of the road, during recent excavations eight metres of wall decoration have come to light.