To be privately owned
Unterdießen Castle

On an old moraine ridge above the municipality of Unterdießen in Upper Bavaria stands Unterdießen Castle, a 16th-century castle complex. Originally built as a Welf fortress on the foundations of a Roman refuge castle, it is now a saddle-roofed building with four corner towers.
History+
The Welfs erected an initial fortress on the remains of a Roman refuge castle. Following a fire in 1589, the Freyberg family undertook its reconstruction, giving the castle its current form. At the beginning of the 21st century, the dilapidated complex was sold to an Augsburg owner, who has since been carrying out renovation and restoration while preserving its historical fabric.
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: 47.9801, 10.8240