To be privately owned
Mannsberg Castle

Mannsberg Castle, a well-preserved medieval complex, is located in Carinthia, Austria, on a southern mountain ridge spur in the Kappel am Krappfeld region.
History+
The first documented mention of Mannsberg Castle, then referred to as "loco Magnesperc," occurred between 1065 and 1075, when the nobleman Adalbero gifted it to the Diocese of Brixen. The name, meaning "Castle of Mangan," refers to a man not historically documented. Between 1162 and 1171, the brothers Hermann and Reginher resided at the castle. In 1301, the castle passed from the Lords of Schrankbaum as a fief to the Carinthian Dukes. A document from this period confirms the existence of a larger upper castle and a lower one. After the extinction of the Counts of Heunburg in 1322 and later the Counts of Pfannberg in 1362, inheritance disputes arose over the property. Duke Albrecht eventually awarded the castle to Count Johann von Cilli.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.at/ktn/kaernten.html
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: 46.7959, 14.4911