To be privately owned
Gronau Manor

Haus Gronau, a former manor and estate house, is situated in Hürtgenwald-Straß in the district of Düren, North Rhine-Westphalia. Originally designed as a moated castle, the quarry stone building was erected in the 17th or 18th century.
There are few records about the early history of the property. Already at the beginning of the 19th century, the house was in private ownership and has since changed hands several times. At the beginning of the 20th century, the complex underwent major structural alterations. Haus Gronau has been a protected monument since July 4, 1983.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:H%C3%BCrtgenwald-Stra%C3%9F-Horm_Denkmal-Nr._13,_Maubacher_Stra%C3%9Fe_2_%28657%29.jpg
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: 50.7430, 6.4257