To be privately owned
Könitz Castle

In the municipality of Unterwellenborn in the Saalfeld-Rudolstadt district of Thuringia, Könitz Castle stands on the Schlossberg. The former hilltop castle is now privately owned.
History+
The origins of the complex likely date back to the 9th century, when a knight named Conz built a wooden castle. Könitz was first documented in 1125, when Adalbert and Christine von Conz transferred their possessions to Saalfeld Monastery, but retained a lifelong right to use the castle. In 1438, the complex passed to the von Hobach family, who reinforced the castle tower with a stone casing in 1450.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=638
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: 50.6514, 11.4894