To be privately owned
Langendorf Castle

One of the best-preserved moated castles in the Rhineland, Langendorf Castle, rises on the outskirts of the eponymous village in Zülpich. Its origins date back to the 12th century, and today it is a late Gothic complex that was once a knight's seat.
History+
The history of Langendorf Castle begins in the 12th century with a noble family named after the locality. The first documented mention as a castle court of the Count of Jülich occurred in 1240. Until the 14th century, a ministerial family, vassals of Jülich, resided here. They were followed by the Lords of Gertzen as owners. Hubert von Gertzen, married to Sophia von Nesselrode, was named as owner in 1447. His son Wilhelm, a bailiff and liegeman, had the castle rebuilt and expanded into a late Gothic knight's seat between 1495 and 1505. After the male line of the Lords of Gertzen died out in 1535, the castle passed to Johann von Palant through marriage. The outer bailey was renovated around 1568/69, and the manor house was remodeled in 1580. After further changes of ownership, including to the families von Binsfeld and von Wachtendonk, Damian Salentin von Harff acquired the castle in 1659.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=568
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: 50.6729, 6.6124