To be privately owned
Dudeldorf Castle

In the northwest corner of Dudeldorf's former town fortifications, in the Bitburg-Prüm district of Rhineland-Palatinate, lies Dudeldorf Castle. It combines medieval origins with later architectural additions.
History+
As early as 1052, a nobleman from Dudeldorf was mentioned. In the 12th century, the original complex consisted of two castles, though their exact time of construction is unknown. The Dudeldorf family died out in the 14th century. The town fortifications, which partly served as the castle's enclosing wall, were built in 1345 and restored between 1451 and 1453. In 1701, Heinrich Gottfried Braun von Schmidtburg acquired the property.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:BurgDudeldorf01.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: 49.9750, 6.6365