To be privately owned
Sorgenfrei Castle

On the slope of the Elsenz Valley lies Sorgenfrei Castle, a hunting lodge. It is located on the southwestern edge of the municipality of Mauer in the Rhein-Neckar-Kreis in Baden-Württemberg and is considered one of the smallest feudal buildings in the region.
History+
At the site of today's Sorgenfrei Castle, a castle known as the “Veste Mure” or “Muren” likely stood around 1200. Field names such as “Burgäcker” and “Schlossäcker” suggest this, indicating that the castle was not built on a mountain. The current hunting lodge was constructed in 1788 by Baron Carl von Zyllenhardt.
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: 49.3336, 8.7913