Fortified by Vauban in the late 17C, this citadel is part of the network of Vauban's Major Sites and was designated a UNESCO World Heritage Site in 2008. Along with Fort Paté, on an islet in the Gironde, and Fort Médoc, on the river's left bank, it is part of the "Verrou Vauban", a network of fortifications erected in the Gironde estuary. In the citadel, don't miss the view of the estuary from the Éguillette tower or the Place d'Armes.