To be privately owned
Bollheim Castle

Bollheim Castle was located in Oberelvenich, a district of Zülpich. Originally built as a moated castle in the marshy lowlands of the Rotbach, it was positioned near an important Roman road. Today, only the farm buildings and gatehouses remain of the original castle.
History+
The first mention of the estate dates back to 1067, when Archbishop Anno II of Cologne transferred the property to St. George's Collegiate Church in Cologne. As a castle, Bollheim was first documented in 1331. Knight Godart von Boylheim is considered the first known owner. The complex changed hands several times, including to the von Vlatten and von Hompesch families. After destruction and a lightning strike in the Middle Ages, reconstruction as a Baroque castle began in 1682. During the Thirty Years' War, in the winter of 1641/42, the castle was occupied by Hessian and Weimar troops.
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: 50.6981, 6.7120