Isteiner Klotz

The position of the Isteiner Klotz on the French border led to the construction of fortifications. Between 1902 and 1907, facilities were built here as part of the Upper Rhine fortifications, but these had to be demolished in 1921 due to the Treaty of Versailles. The re-fortification of the Isteiner Klotz began in 1936 as part of the Westwall under Nazi rule. By the end of World War II, 113 military bunkers had been built around Istein. With wall and and ceiling thicknesses of up to 3.5 meters, these facilities were the most heavily fortified of the entire Westwall on the Upper Rhine. The main installations were located underground in the rock and were connected by a system of tunnels, stairs, and elevators over two kilometers long.