To be privately owned
Minoriten Castle

The Minoriten-Schlössl, a small castle, is on Graz's Rosenberg in the third district of Geidorf.
History+
The origins of the Minoriten-Schlössl date back to the late 16th century. Between 1596 and 1597, the regional secretary Stephan Speidel zu Vatersdorf commissioned its construction on his land. Upon its completion in 1603, it was named "Speidelsegg". In the same year, it was visited by the Bishop of Lavant, Georg Stobäus von Palmburg. Speidel's brother Sebastian continued the construction work, and from 1618, the estate became known as "Rosegg".
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Minoriten-Schl%C3%B6ssl_Graz.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: 47.0908, 15.4468