To be privately owned
Wildberg Castle

In the municipality of Irnfritz-Messern, northwest of Horn in Lower Austria, stands Wildberg Castle. The structure, once a fortified stronghold, was transformed into a Renaissance castle.
History+
The first documented mention of the complex as Burg Wiltperch dates back to the 12th century, when it was owned by the Lords of Wildperch. In the early 13th century, after the male line of Hohenburg-Wildberg died out, the castle passed as a princely fief to the Counts of Vohburg. Later, it came into the possession of the Lords of Maissau.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:GuentherZ_2012-09-16_0103_Messern_Schloss_Wildberg.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: 48.7162, 15.5282