To be privately owned
Hunnenbrunn Castle

A late medieval estate in Carinthia, Austria, was expanded into Hunnenbrunn Castle in the 16th century and now serves as an agricultural vocational school.
History+
The origins of Hunnenbrunn Castle trace back to a rural estate belonging to the Hunnerbrunner family, which was part of the Kraig dominion. After the Kraiger family died out in 1564, ownership passed to the Counts of Hardegg. In 1570, Georg Freiherr von Khevenhüller acquired the estate and had a small Renaissance castle built in place of the farmhouse. The Khevenhüller family owned the castle until 1619, when Paul Freiherr von Khevenhüller was forced to emigrate due to the Counter-Reformation. Subsequently, the castle frequently changed hands, primarily belonging to merchant and citizen families from St. Veit. Later owners included the Zenegg family, the imperial mint master Hans Georg Pero, and mayor Johann Jakob Kärner. In 1686, Franz Andreas von Mayerhoffen acquired the castle and its dominion, which remained in the possession of his descendants until 1806.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Hunnenbrunn_Schloss_05.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: 46.7814, 14.3722