Forteresse de Châtel-sur-Moselle

The Châtel-sur-Moselle fortress is one of the largest castles in Europe. It covers five hectares, has 22 towers, a 1.4-kilometer-long city wall and three floors full of galleries and underground spaces.

The fortress was built in the 11th century and has been extended over the centuries. In the winter of 1670/71 it was destroyed by the troops of Louis XIV.
Some areas of the complex can be visited, as well as a museum with finds and information about the fortress.

The fortress of Châtel-sur-Moselle in Châtel-sur-Moselle in the Vosges is one of the largest fortresses in Europe. It covers five hectares, has twenty-two towers and 1.4 km of ramparts, three floors with galleries and underground rooms. The fortress testifies to the development of the fortification from the eleventh to the sixteenth century and an early adaptation to artillery with metal balls (Wikipedia).