To be privately owned
Lauksburg Castle (Ruin) (Espenschied)

The Lauksburg ruin, a small complex, is located in western Hesse, near the Espenschied district of the city of Lorch am Rhein. It is a spur castle about 50 meters above the Wisper stream and the Laukenmühle. Its feature is the surviving residential tower.
History+
The origins of Lauksburg are obscure, but its construction is presumed to date back to the early 12th century. The Archbishopric of Mainz is mentioned as a former owner. As early as 1575, the castle was described as dilapidated in a document. No restoration took place, likely due to its minor strategic importance and limited size, which made it unsuitable for permanent residential use.
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: 50.0988, 7.9118