To be privately owned
Waldenfels Castle

Near Reichenthal in the Upper Austrian Mühlviertel, Waldenfels Castle is at an altitude of approximately 667 meters above sea level. Originally built as a castle in the 13th century, it has been in private ownership for centuries.
History+
The origins of Waldenfels Castle date back to the 13th century, with the construction of the first castle around 1290 attributed to the brothers Heinrich and Eberhard von Wallsee. Its first documented mention as a refuge castle occurred in 1300. After changing owners, including Otwin Waldburger and the Starhembergers, the complex was destroyed by Hussites in 1474. Reconstruction followed as a residential castle without a keep. In 1584, Joachim Stängel acquired the castle from Emperor Rudolf II.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Reichenthal_Waldenfels.jpg
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: 48.5394, 14.3889