The Castle can be visited
Trifels Castle

In the Palatinate Forest above the small town of Annweiler am Trifels stands Trifels Castle, a rock castle. In the High Middle Ages, it gained importance as an imperial castle for over two centuries and is now a protected cultural heritage site.
History+
First documented in 1081, Trifels Castle was initially owned by a nobleman named Diemar. In 1113, it was elevated to an imperial castle. Between 1125 and 1298, it repeatedly served as a repository for the Imperial Regalia of the Holy Roman Empire.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=1456
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: 49.1965, 7.9785