To be privately owned
Rossdelle Castle

Haus Rossdelle, often referred to as a castle, is a fortified house on the Rinderbach in the Vogelsangbach Valley. It was once a feudal estate of the Imperial Abbey of Werden and is now a protected monument, whose exact period of origin is estimated to be no earlier than the 16th century.
History+
The first documented mention of the property, then known as Rosendelle, appears around 1400 in the Werden Urbar. In 1474, Haus und Hof Rosendelle was given to Provost Wilhelm von Reifferscheid as a retirement home, where he lived until 1506. After his death, it was leased in 1513 first to Angermund Herman von Else, a Bergisch district judge, and later to Reinhard von Landsberg.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=583
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: 51.3352, 6.9606