The castle in North Rhine-Westphalia that served as the SS headquarters from 1934 to 1945. 

The work involved in the construction of the Wewelsburg was carried out by forced labourers. These were mainly political prisoners from Germany and the occupied territories. For this purpose, a concentration camp was established at the foot of the castle: KZ Niederhagen. It was the smallest independently administered concentration camp of the Third Reich, but had a relatively high death rate due to the harsh regime.