KZ Niederhagen was the smallest German concentration camp during WW II. It was located near Wewelsburg, the castle in North Rhine-Westphalia that served as the SS headquarters from 1934 to 1945.  The camp was put into use in May 1939, then as a subcamp of Sachsenhausen. From September 1941 it became an independent concentration camp. In total 3,900 people were imprisoned in Niederhagen, half of whom died there.

The former camp kitchen is now a fire station, the gatehouse a 2-person home. On the former roll call square a triangular monument.