The Barrage Vauban is a weir (barrier across a river designed to alter its flow) erected in the 17th century on the river Ill west of the 'Petite France' district in Strasbourg. It was constructed from 1686 to 1700 by the French Engineer Jacques Tarade according to plans by Vauban. Several stories high, it houses sculptures in its main level and a panoramical terrace on its roof.References:
The Château Comtal (Count’s Castle) is a medieval castle within the Cité of Carcassonne, the largest city in Europe with its city walls still intact. The Château Comtal has a strong claim to be called a 'Cathar Castle'. When the Catholic Crusader army arrived in 1209 they first attacked Raymond-Roger Trencavel's castrum at Bèziers and then moved on to his main stronghold at Carcassonne.
The castle with rectangular shape is separated from the city by a deep ditch and defended by two barbicans. There are six towers curtain walls.
The castle was restored in 1853 by the architect Eugène Viollet-le-Duc. It was added to the UNESCO list of World Heritage Sites in 1997.