Ouvrage Bois-du-Four, Military fort and museum in Villers-la-Montagne, France.

Ouvrage Bois-du-Four is a single-block Maginot Line fortification on a rise in Villers-la-Montagne, built as a unitary double casemate. Its one combat block stands on two levels, with three automatic rifle cloches, an observation cloche, a machine gun turret, and embrasures for anti-tank guns and mortars. A short gallery reaches 30 metres deep, and the concrete facade retains deep openings and a wire entanglement.

Approved in May 1932, Bois-du-Four was built by the Paris contractor Monod for 9 million francs as a single infantry block, the only part of a planned five-block artillery ouvrage. In June 1940 the German 183rd Division weighed an attack between Bois-du-Four and Mauvais-Bois but chose to strike farther east; the garrison of 135 men and 2 officers under Lieutenant de Mecquenem surrendered on 27 June. German occupiers then stripped its equipment.

The site is maintained by an association that has restored the surface, including 40 living areas. It displays 15 major frescoes removed from other Maginot Line works and restored here, two of them by Robert Humblot. Outside, a memorial to the crew features a Renault FT tank turret, a reconstructed 1939 trench, a campaign hut, an entrance sentry box and an interval command post.

The site sits on the highest point of the Pays de Longwy, with a free natural car park and a picnic area on the secured grounds. Guided tours leave at set times on Sundays from June to September, and groups can book year-round. The surface restoration covers 40 living spaces, while a short gallery lies 30 metres deep.

The association that has maintained the site since 1992 restored the surface completely, covering 40 living areas, and gathered 15 major frescoes taken from other Maginot Line works, two of them by the painter Robert Humblot. Outside stand a memorial with a Renault FT tank turret, a reconstructed 1939 trench, a campaign hut and an interval command post.