Four-à-Chaux is a gros ouvrage of the Maginot Line, located in the community of Lembach, France. The name comes from the French for ‘Lime Kiln’ as the fort is built on the site of a former limestone quarry and associated kiln.
The personnel and ammunition entrances are, as usual, separate structures. Unusually, the route to the main tunnel level for ammunition leads down an inclined plane rather than the usual lift. There are six fighting blocks, with weaponry that includes machine guns, 47mm anti tank weapons, 75 and 125mm guns and grenade and mortar launchers. Over 4km of underground galleries link the blocks.
The site was attacked by the Germans during the invasion of France in June 1940 and it surrendered later the same month. After the end of the war the fort was refurbished for use during the Cold War. It is now operated as a museum for guided tours which are also available in English by prior arrangement.