The remains of the Castle can be visited
Altdahn Castle

The castle ruin of Altdahn is a rock castle in the southern Palatinate Forest near the town of Dahn in Rhineland-Palatinate. It is part of a group of castles built on a ridge.
History+
Presumably built at the beginning of the 13th century, Altdahn Castle was first documented in 1236 when Friedrich von Dahn administered it as a vassal of the Speyer bishop Konrad IV von Dahn. In 1363, Altdahn was devastated in a feud between the Dahners and the Fleckensteiners, but was repaired. Another destruction occurred in 1372, followed by another in the War of the Four Lords in 1406.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=1477
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: 49.1500, 7.8020