To be privately owned
Reck Castle

In Hamm-Pelkum-Lerche, North Rhine-Westphalia, is Haus Reck. Originally known as “Haus zur Heyde,” it adopted its current name in the mid-16th century and served as the ancestral seat of a branch of the von der Recke family. The complex features architecture spanning several centuries.
History+
Haus Reck was first documented in 1465 when it was expanded into a fortified castle. The core of the current manor house dates back to the 15th century. In the 16th century, a Bauhaus, a defensive wall, and a fortified tower made of plastered green sandstone were added.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=636
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: 51.6240, 7.6900