The remains of the Castle can be visited
Weißenstein Castle (Ruin) (Wehrda)

The Weißenstein Ruin, a former hilltop castle, is situated above the Lahn Valley near the Marburg district of Wehrda. Its name derives from the white sandstone outcrop on which it was once built.
History+
Archaeological findings indicate that the site of Weißenstein Castle was already in use during prehistoric times, with some of the existing ramparts possibly dating back to the Iron Age. The construction of the castle began in the 8th or 9th century with a square building. Until the 11th century, the complex was expanded. Ring walls, a residential tower, a triangular annex, and a dwelling house with a pentagonal tower were added.
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: 50.8489, 8.7547