The remains of the Castle can be visited
Bilenstein Castle

East of Kaiserslautern in Rhineland-Palatinate is the Bilenstein Castle Ruin, a former rock castle. It is now a natural and cultural monument.
History+
Presumably in the 12th century, the castle was built under Duke Frederick II of Swabia. By 1185, it was already in the possession of the ministerialis Merbodo von Beilstein, who sealed as a witness in 1212. King Henry VII permitted the reconstruction of Castrum Bylenstein in 1234. Between 1420 and 1455, the castle suffered violent destruction and was not rebuilt thereafter. It passed into the possession of the Flörsheimer family and the Electoral Palatinate. A last Beilsteiner was mentioned in 1464.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=1502
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: 49.4331, 7.8456