To be privately owned
Horst Castle

Haus Horst, also known as Horst Castle, is a former noble residence on the northern bank of the Ruhr river in the Horst district of Essen. This structure is now protected as both a building and an archaeological monument.
History+
The exact time of Haus Horst's construction is unknown, but a possible connection to the neighboring Vryburg is speculated, both located at an ancient Ruhr ford and a branch of the Hellweg, possibly serving to protect it. The noble family of the Lords of Horst is documented since the 12th century. Members of this family, such as Heinrich von Horst (1280 as Drost of the Counts of Berg) and Hugo von Horst (1282 as Marshal of the Abbess of Essen), attained ministerial status and were among the most influential families in the Imperial Abbey of Essen. The noble seat itself, however, is only mentioned in 14th-century documents, with a rural estate having stood on the site previously. After the Lords of Horst died out around 1400, the estate frequently changed hands, including Bernd von Voerst (1457), the von Schüren family, Alexander II von Velen (1644–1652), Johann Heinrich von Reede (1663), and Jobst Dietrich Freiherr zu Wendt (1674). In the early 19th century, Haus Horst was leased by the Wendt auf Hardenberg family. In 1840, Friedrich Ludwig Niemann had the current Villa Vogelsang built on the western grounds.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=575
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: 51.4321, 7.1168