Important relics remain of the three perimeter walls which successively protected the town. In particular, you will see some remains of the Roman perimeter wall from the 1C, which was reinforced by the Visigoths in the 7C between the palaces of the dukes of Cadaval and the counts of Basto. The 14C medieval perimeter wall bordered the town to the north and the west, and the fortifications built in the 17C in the Vauban style bound the public gardens to the south of the town.