To be privately owned
Gößweinstein Castle

In Franconian Switzerland, high above the market town of Gößweinstein, stands Gößweinstein Castle. This fortress in Bavaria is said to have inspired Richard Wagner for the Grail Castle in his "Parsifal."
History+
The origins of Gößweinstein Castle date back a long way. It was probably named after Count Gozwin, who died in 1065 during an incursion into the territory of the Bishop of Würzburg. The first written mention of "Goswinesteyn" appears in 1076, when Emperor Henry IV imprisoned Bishop Burchard II of Halberstadt there during the Saxon War, suggesting a strong fortification even then. Later, the castle was documented as property of the Diocese of Bamberg and served as the seat of a bailiwick for the Bamberg bishops from 1348 to 1780. During the Peasants' War in 1525, the complex suffered destruction but was rebuilt.
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: 49.7704, 11.3343