To be privately owned
Patthorst Castle (Steinhagen)

Patthorst Castle in Steinhagen, North Rhine-Westphalia, is a manor house situated on a moated island. Originally a hunting lodge for the Counts of Ravensberg, it evolved into a noble residence and remains in private ownership to this day.
History+
The origins of Patthorst Castle date back to the late 14th century when it became the ancestral seat of the von Closter family. Wilhelm von Closter received the estate as a fief in 1463. The von Closter family inhabited the property for centuries until their lineage ended in the early 19th century. The heiress was Therese von Closter, who married Karl Christian Heinrich von Eberstein in 1803. He was listed as the owner of the manor from 1830. A site plan from 1822 depicts Patthorst as a moated castle with a manor house and outbuildings.
Source: Wikipedia · Licence: CC BY-SA 4.0
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: 52.0097, 8.3818