Built out of Ardennes sandstone in the 11C, this castle was fortified in the 16C by the Dukes of Guise. Strengthened by Vauban in the 17C but the target of shelling in 1914-18, it was restored from its ruined state in the 1950s. Your visit takes you through the maze of vaulted rooms to the artillery casemates, the archaeology museum with its display of pieces unearthed during the excavations, and the keep. A succession of underground passageways brings you to the Bastion de la Haute-Ville and the so-called "Lepers' Gallery".