To be privately owned
Bergfeld Castle

A former hunting lodge in the Volcanic Eifel, Bergfeld Castle, stands on a plateau near Eisenschmitt. It was conceived as a retreat for hunting, later expanded into a family residence, and once hosted Emperor Wilhelm II as a guest.
History+
The Düsseldorf entrepreneur Hugo von Gahlen commissioned the castle's construction in 1900, after acquiring the surrounding Franzosenwald forest. Architect Max Wöhler designed the building, which today forms the western part of the estate. An expansion followed in 1911 to make it suitable as a permanent family residence. Three years later, in 1914, a separate building with a bowling alley was added. Von Gahlen resided at the castle until his death in 1938. It remained in the possession of his descendants, the von Berghes family, until 1998. During World War II, it temporarily served as the headquarters for the General Staff of the VII Army.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:Schloss_Bergfeld_Nordseite.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 50.0528, 6.7136