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

The Freienfels Ruin, a spur castle, is on a rocky outcrop on the left bank of the Weil in Hesse. Its strategic location near the former residential city of Weilburg and on trade routes once made it a stronghold in the region.
History+
The construction of Freienfels Castle is presumed to have taken place around 1300, likely by Counts Heinrich and Reinhard von Diez-Weilnau. It was probably intended to counteract the ambitions of Count Adolf von Nassau. The castle was first documented in 1327 in Siegfried von Runkel's will. In 1331, it was sold to Count Gerlach von Nassau. By the end of the 14th century, the castle had lost its military significance, and in 1466, already dilapidated, it was enfeoffed to Johann von Schönborn. The Schönborn family owned the castle for approximately 220 years before it was sold to Johann Ernst Freiherr von Friesensee in 1687.
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: 50.4568, 8.3005