The remains of the castle can be visited
Stein Castle

The Stein Castle remains are the remnants of a hilltop castle in northwestern Thuringia. Situated above the village of Lengenfeld unterm Stein, they today offer an insight into bygone eras.
History+
The Stein Castle was first mentioned in documents in 1409, although the name "Stein" had appeared in the region before, but could not be clearly assigned to this particular complex. It is presumed that a Tuto de Lapide was already residing on the rock above Lengenfeld around 1234. The castle was later handed over by Archbishop Gerhard I of Mainz to Gottschalk von Plesse, who sold it to Duke Albrecht of Braunschweig in 1282. Around 1300, the complex came into the possession of the Lords of Hardenberg, until Archbishop Matthias von Buchegg reacquired it in 1326.
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: 51.2220, 10.2067