The Castle can be visited
Wildberg Castle

Wildberg Castle, a high-altitude castle partially preserved as a ruin, is on a mountaintop in Kirchschlag bei Linz in the Urfahr-Umgebung district of Upper Austria, Austria. It is the oldest castle complex in the Mühlviertel region and has been owned by the Starhemberg family since the High Middle Ages.
History+
The first documented mention of Wildberg Castle dates back to 1135. It was built by the noble family of the Haunsperger. In 1198, the fief passed to Gundaker II of Steyr, an ancestor of the Starhemberg family, who still own the castle today. A historical event occurred in 1394 when Bohemian King Wenceslaus was briefly imprisoned here. In the mid-16th century, a Renaissance building with arcades was constructed. A fire in 1654 caused damage, which was repaired. From 1664/65, a palace was built on the site of the former outer bailey. By around 1750, the Wildberg dominion encompassed 703 subjects.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Wildberg-1.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: 48.4027, 14.2947