To be privately owned
Nesselrath Manor

In Leichlingen-Leysiefen in the Rheinisch-Bergischer Kreis is Rittergut Nesselrath, a historic manor and estate house. Originally built as a medieval knight's seat, its history dates back to the early 14th century.
History+
The first documented mention of the estate, also known as Haus Nesselrode, dates back to 1303. It was built and inhabited by the noble family Nesselrode, who belonged to the Bergian ministerial nobility. In 1511, ownership transferred to the noble family Ketteler, who extensively remodeled the knight's seat in 1536.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.zeche.org/
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: 51.1296, 7.0308