The remains of the Castle can be visited
Reinsburg Castle (Ruin) (Reinsfeld)

At approximately 605 meters above sea level in the Thuringian Reinsberge mountains stands the Reinsburg ruin, once a ridge castle. Its foundation walls are the remains of what was once the largest fortification on the slopes of the Gera.
History+
The exact construction date of the Reinsburg is unknown, but earthworks suggest an earlier ringfort that predated the medieval structure. The castle was likely conquered and destroyed around 1289 or 1290 during a campaign by King Rudolf of Habsburg. This campaign aimed to enforce regional peace and led to the demolition of a total of 66 castles in Thuringia.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Aschroet / CC0 via Wikimedia Commons
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: 50.7694, 10.9388