Built as Ordensburg Vogelsang in the 1930s to educate leaders of the Third Reich. During the war it was a refugee centre and military base. After the war the Brits took control of it until 1950 and then it became a Belgian military base until 2006. Now it is open to the public, including the surrounding terrain. Now it is called Vogelsang IP (=International Place).
I learnt about Vogelsang from latium, a flickr contact of mine. He visited Vogelsang in the 1960s when he served in HM Army (16/5th Lancers), see for instance here: www.flickr.com/photos/10804277@N08/3178270072/ and here: www.flickr.com/photos/10804277@N08/2628053663/
More info on Vogelsang: www.thirdreichruins.com/vogelsang.htm