A triumph of 17th-century engineering, the Barrage Vauban bears the architectural imprint of the leading French military engineer of the age – Sébastien Le Prestre de Vauban. The dam has been restored to its former glory and is now free to visit. Ascend to the terrace for a tremendously photogenic view that reaches across the canal-woven Petite France district to the Ponts Couverts and cathedral spire beyond.