Fort_l'Ecluse

Fort l'Écluse, or the Fort de l'Écluse, is a military fort in Léaz, Ain, close to Collonges in Eastern France. It commands the Rhône Valley as a natural entrance into France from Switzerland between the Vuache and the Jura Mountains.
The fort, which was established by a Duke of Savoy, was completed by Sébastien Le Prestre de Vauban during the reign of King Louis XIV. It was destroyed by the Austrians in 1815, but rebuilt by the French; at the same time it was considerably strengthened and heightened. The high-road intersects a portion of this fortification.