To be privately owned
Lupburg Castle (Ruin)

The Lupburg Ruin is in the municipality of Lupburg in the Bavarian district of Neumarkt in the Upper Palatinate. This hilltop castle has its origins in the 12th century.
History+
Lupburg Castle was likely built in the 12th century by a nobleman named Ludewicus, who was a vassal of the Burgrave of Regensburg. Its first documented mention dates back to 1129. In 1299, the castle passed into the possession of the Prince-Bishopric of Regensburg, and in 1505, it became part of Palatinate-Neuburg. From 1803, the complex was privately owned and fell into disrepair, but it underwent renovation in the 20th century.
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: 49.1562, 11.7553