Kastels, Artillery fortress in Graubünden, Switzerland

Kastels (army designation A 6400) is a rock-cut artillery fortress of the Swiss Army on the Castels hill above Mels in the Seeztal. Its three 10.5 cm turret guns were disguised as rocks and barns, and two 7.5 cm bunker cannons were added. The war command post of the whole Sargans fortress area lay in the lower storey.

Planned in 1939 as the central command work of the Sargans fortress area, Kastels was carved into the rock above Mels and finished in 1943. Its three 10.5 cm turret guns were the first of their kind in Swiss fortress artillery; two were ready in October 1940 and the third in July 1941. The war command post was first occupied on 12 September 1943, and the work was decommissioned under Army Reform 95.

The site's name lives on in army records as Werk A 6400, and the hill itself was walled in prehistoric times, with watchtowers at its west and east ends. After secrecy was lifted at the end of the Cold War, part of the rock complex still serves occasionally as an underground troop shelter and as a command centre for security at the World Economic Forum in Davos.

The rock works lie above Mels on the Castels hill; the gun turrets were disguised as rocks and barns, so look for these shapes rather than a castle. Part of the complex is still occasionally used as an underground troop shelter and as a command centre for security at the World Economic Forum in Davos, so access is not freely open.

The hilltop held a prehistoric rampart with a wall around the plateau and two watchtowers, west and east, before the modern work existed. The 1940s gun turrets were disguised as rocks and barns, so from outside the artillery position above Mels reads as ordinary terrain.