To be privately owned
Schrecksbach Castle

The Old Burghaus Schrecksbach, also known as the Old Castle, is a historic fortified house in Schrecksbach, a municipality in the Schwalm-Eder district. It once served as a noble residence.
History+
The noble seat was built between 1580 and 1592 by the von Langenstein called Gonzenrod family. It is believed that a predecessor building existed on the Schrecksbach hill. After the division of the Landgraviate of Hesse in 1567, Schrecksbach became the southern border town of Hesse-Kassel, leading to the fortification of the town with defensive structures and castle-like noble residences. A unique feature was a system of underground passages connecting several noble seats, which offered protection to villagers during the Thirty Years' War, particularly on Christmas Day 1635 during an attack by Croatian mercenaries.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=1367
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: 50.8338, 9.2872