The remains of the Castle can be visited
Wallenstein Castle

The Wallenstein Castle Ruin is a high medieval hilltop castle, located in the Wallenstein district of the municipality of Knüllwald in North Hesse.
History+
The spur castle was presumably built in the 12th century by the Hersfeld Abbey to secure its western territories against the Thuringian Landgrave. In the early 13th century, the castle came into the possession of Count Albert V of Schauenburg, who subsequently called himself Albert of Wallenstein. Part of the castle was sold back to Hersfeld Abbey in 1250. Albert (I) of Wallenstein later moved his main residence to the newly built Neuwallenstein Castle. During the Thirty Years' War, specifically in 1637, the castle was destroyed by Croatian imperial troops and was not rebuilt thereafter. After the war, the entire Hersfeld region, and thus the ruin, fell to the Hessian Landgraves.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=1367
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: 50.9511, 9.4939