To be privately owned
Mallinckrodt Manor

Haus Mallinckrodt is a manor and estate house located on the western slope of the Ardey Hills in Herdecke. It is often mistakenly referred to as a castle. It lies in a forest above the Ruhr valley.
History+
The origins of the estate date back to around 1241, when it was known as “Mesekenwerke.” Later, its inhabitants adopted the name von Mallinckrodt. The complex was initially a fief of the Counts of Volmarstein and later passed to the Counts of the Mark. In 1446, the castle was burned down by Dietrich II von Moers. Another fire destroyed the complex in 1619.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=571
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: 51.4004, 7.3608