To be privately owned
Prandegg Castle

The Prandegg castle ruin is a former hilltop castle, rising on a rock ridge in Schönau im Mühlkreis, Upper Austria. Its elongated shape adapts to the terrain.
History+
The first documented mention of Prandegg Castle dates back to 1287. Originally, the feudal lordship was divided: one half belonged to the Bishop of Regensburg, the other was a sovereign fief. In the early 13th century, the Regensburg share came into the possession of the Pranter family, later to the Reichenstein and Capeller families. The latter acquired both halves by 1352 and held the castle until their extinction in 1406. Afterwards, Prandegg was divided again and passed through marriage to the Dachsberger and Liechtenstein families. In 1534, the emperor enfeoffed Hilleprant Jörger with a part of the castle; two years later, he acquired the second half and bought the lordship free from feudal sovereignty. The Jörgers united the lordships of Prandegg and Zellhof and resided in the castle until they had to sell their property in 1631 as Protestants. After several changes of ownership, including the Scherffenberger, Starhemberger, and Salburger families, the castle gradually fell into disrepair. In 1823, the Dukes of Saxe-Coburg and Gotha acquired the complex, which has remained in their family's possession to this day.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Google Hupf
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: 48.4147, 14.6667