Following Rue du Bas-Val, you will reach the Promenade du Val and find the Saint-Pierre postern, the well-preserved northern and eastern parts of the town walls, as well as the Vilaine valley and the former Rachapt quarter. The Saint-Pierre postern, to the north, was one of the four gateways used to access the fortress. Dating back to the 13th-15th centuries, it is the only remaining gateway. The three others were the Porte d’Enbas to the west, the Porte de Gâtesel to the south and the Porte d’En-Haut to the east. A postern is a gateway hidden within the town wall, designed to be as unexposed as possible. Pedestrians and horse-riders were allowed to pass through it, while horse-driven vehicles were forbidden.