The NS-Ordensburg Vogelsang is a former training camp of the Nazi NSDAP in the German Eifel. Built between 1934 and 1936 to a design by Clemens Klotz, it housed 500 recruits until the start of the Second World War.
In the Ordensburg, the Nazis indoctrinated recruits between the ages of 25 and 30 in their racial doctrine.
It was built between 1934 and 1936 by order of the National Socialists, but in retrospect it was not a great success, since they only ran the program until 1939. The training program came to a standstill again at the start of the Second World War, after which the barracks were used by the German Wehrmacht.
After World War II, Vogelsang became a military training area for various NATO countries; first for the British used it and from 1950 until 2005 it was used by the Belgian armed forces. The Dutch Army also often stayed at the base.
Nowadays it is in use by (among other things) a national nature park (a wonderful area for walking), a red cross museum, but especially a museum about the use of this complex in around the 2nd world war. On one hand that's understandable, on the other hand it has only been in use for that particular purpose for only a couple of years, after which it has been in use for many(!) more years in the Cold War by the "west powers". And that part is almost impossible to find in the descriptions.... A missed opportunity as far as i can see it.
See: https://www.eifelinfo.nl/ordensburg-vogelsang/ for more information.