Artilleriewerk Naters, Military fortress and museum in Naters, Switzerland

The Artilleriewerk Naters is an underground military complex with roughly one kilometer of tunnels containing gun positions, machinery rooms, kitchens, dining areas, and sleeping quarters for 200 soldiers. The rooms remain in their original state and demonstrate the practical layout of such a fortress.

The complex was built between 1939 and 1943 to protect the Brig transportation hub and the road over the Simplon Pass during the second world war. It was equipped with four 7.5 centimeter cannons and served as part of Switzerland's defense strategy.

The fortress is now the Simplon Fortress Museum «La Caverna», run since 2008 by the friends' association after the municipality of Naters bought the site from the Confederation in 2005. Two former 10.5 cm ammunition magazines house the Swiss Guard Museum, and since 2016 the Swiss Radiation Museum has also been shown inside the works.

Visitors can explore the original installations on guided tours, including former ammunition storage areas that now contain exhibitions. The underground can be cool, so appropriate clothing is recommended and the passages require steady footing.

The site housed one of five vaults belonging to the Swiss National Bank for gold and valuables, featuring a secured room measuring 5 by 6 meters. This treasure was kept secret as part of the defense strategy and served an important role in the country's financial security.