The remains of the Castle can be visited
Haselstein Castle (Ruin)

The Haselstein Ruin, a hilltop castle, stands on a steep basalt cone in Nüsttal, Hesse.
History+
The origins of Haselstein Castle likely date back to the 11th century, possibly even earlier, built by the Lords of Haselstein. The basalt cone itself was first documented as “Haselahastein” in 780/781. In 1119, the castle was conquered by Abbot Erlof von Bergholz of Fulda to put an end to the brigandage practiced there. Wigger von Hasela is known as the first lord of the castle, mentioned in 1135. After another conquest in 1156, the castle definitively became property of the Fulda monastery and subsequently served as the seat for Fulda officials. These included the Lords of Haselstein until their extinction in 1330, as well as the Lords von der Tann, who administered the Haselstein office from here.
Source: Wikipedia · Licence: CC BY-SA 4.0
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: 50.6809, 9.8508