The remains of the Castle can be visited
Brandenfels Castle (Ruin) (Markershausen)

The castle was built in 1248 by the Lords of Boineburg. In 1260, the castle was unsuccessfully besieged during the Hessian-Thuringian War of Succession. Later, it came into the possession of the Landgraves of Thuringia through a treaty. They granted the castle as a hereditary fief to the Treusche von Buttlar. In 1326, the Archbishop of Magdeburg was captured near Eisenach by the Lords of Buttlar and held captive at Brandenfels Castle for ransom. In 1384, due to highway robbery, the castle was besieged by Landgrave Balthasar of Thuringia with the imperial cities of Erfurt, Mühlhausen, and Nordhausen. The siege failed.
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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: 51.0419, 10.1047