To be privately owned
Randerath Castle

In the Randerath district of Heinsberg in North Rhine-Westphalia stands Randerath Castle, a historic defensive structure. Originally built on a motte, it was once the ancestral seat of a noble family.
History+
The origins of Randerath Castle date back to around 900, when it was built on an artificial mound (motte). Its first documented mention was in 1157. As the ancestral seat of the noble family of Randerath, the castle became the center of a noble lineage whose influence extended to Linnich. In 1392, the complex came into the possession of the Dukes of Jülich, who fortified it. After its destruction in 1542, the castle was described as a ruin in 1609. From 1656, a glassworks operated within the castle grounds.
Source: Wikipedia · Licence: CC BY-SA 4.0
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: 51.0145, 6.1770