To be privately owned
Hardeck Castle

Hardeck Castle is located in the municipality of Neualbenreuth, Tirschenreuth district in the Upper Palatinate, Bavaria, a stone's throw west of the Sibyllenbad spa in the small village of Hardeck. It is 24x12 meters in size and stands on a 15-meter-high, steeply rising granite schist rock nose amidst park-like grounds with a beautiful view of the southern landscape.
From Robert Giersch "Source Research on the Agricultural and Building History of the so-called Fraisgebiet", 1996:
The village of Hardeck plays a special role (in the municipal association): The properties of this settlement are grouped around Hardeck Castle, a former imperial castle, first mentioned in 1238, which once belonged to the ring of Staufer castles around the Eger Palatinate Castle. In the 18th century, it was the seat of the Hardeck collegiate court... The official castle (house no. 14) was to be sold after the secularization in 1803, but no buyer was found. The castle building was rented out until 1847, then it was acquired by the master dyer Johann Ruderer, who set up a dye works here.
13th and 14th Century
The predecessor of the current castle was a medieval fortress. This was referred to as castrum Hardekke in 1316, as veste Hardeckh and as munitio Hardeck in 1434. When and by whom it was built is not known. Presumably, the castle served as an Egerian ministerial seat and a fortification against predatory Wends.
When Rudolf I and King Wenceslaus II of Bohemia met in 1289, Egerland knights were in their retinue, including an Albrecht von Hardeck. The name also suggests an early origin. Hard is an old term for forest, eck means a fortified complex.
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: 49.9859, 12.4171