Citadelle de Dinant Wallonia

Though sparse on sights, this vast, unadorned 1818 citadel looms menacingly on its clifftop, offering toe-curling views high over town. The entrance price includes the cable car to the top, though you can take on the 408 steps if you need to work off lunch. Once there, it's worth taking a free one-hour tour through the fortress, with guides describing some of the key moments in Dinant's past.