The keep and the gate are part of the of medieval ramparts which still surround the old town. It is called Donjon de la duchesse Anne (Keep of the Duchess Anne), and stands 111 feet (34m) high near the Saint Louis gate. John V, Duke of Brittany built the keep in 1382-1383. The keep is formed by a union of two tall circular towers; a moat and drawbridge divides the keep from the outside of the ramparts as well as from the inside of the city, providing a stronghold both against outsiders and from the townspeople themselves. Extensive machicolations overhang the wall head providing defensive coverage of the base of the tower.