Magletsch, Artillery fortress in Gretschins, Wartau, Switzerland

Magletsch is an underground artillery fortress driven into limestone near Gretschins in the municipality of Wartau, canton St. Gallen. Its roughly 4,000 metres of tunnels, which had to be lined with concrete, link quarters for 381 men, a bakery, a laundry, a 70-bed hospital, two water reservoirs holding 1.6 million litres, and three diesel engines. Three armoured turrets with 10.5 cm guns, four 7.5 cm bunker guns and ten machine-gun positions made it one of the strongest works of the Sargans fortress. Above the entrance, a pale green double door under a wide concrete overhang carries a yellow sign reading "LA LOURDE"; a weathered wooden hut marked "LA LOURDE 4" stands beside it.

Construction took place between 1939 and 1941 as part of Switzerland's defensive strategy during World War II. It served as a fortified position along the northern border zone to counter potential threats from neighboring regions.

The museum is run by the Artillerie-Fort Magletsch association, which rented the combat and infrastructure sections from the defence ministry and opened them on 1 July 2000. Visitors walk the roughly 4,000 metres of tunnels driven through limestone and lined with concrete, past the paternoster ammunition hoists serving the 10.5 cm turret guns. The site's army designation is A 6020, "Der Hammer".

Access is by guided tour only, offered during the summer months for organized groups. Wear comfortable shoes as the route involves narrow passages and stairs throughout the underground complex.

Three diesel engines from the World War II era remain installed in the original engine room deep underground. These motors powered all building systems through a network of fuel storage tanks carved into the rock.