To be privately owned
Arff Castle

A former moated castle, Schloss Arff is located in the Cologne district of Roggendorf/Thenhoven. It once served the nobility as a summer residence.
History+
The first mention of the Knights van der Arffe, who gave the castle its name, dates back to 1366. In 1572, the estate passed into the possession of Albrecht von Baexen through his marriage to Catharina von der Arff. The original building was destroyed during the Truchsessian Wars between 1583 and 1586. Adam von Blittersdorf sold the estate in 1750 to the von Buschmann family, who then had the current castle built between 1750 and 1755.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.zeche.org/
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: 51.0510, 6.8160