The remains of the Castle can be visited
Reichenberg Castle

The castle ruin Reichenberg, a medieval castle complex, is situated above the municipality of Reichenberg in the Rhein-Lahn district of Rhineland-Palatinate. It has been part of the UNESCO World Heritage Upper Middle Rhine Valley since 2002.
History+
Construction of Reichenberg Castle began in 1319 under Count Wilhelm I of Katzenelnbogen. By his death in 1331, only the habitable shield wall with two tall flanking towers, the eastern outer bailey, and the foundations of the western main castle were completed. After an inheritance division in 1352 between Eberhard and Wilhelm II of Katzenelnbogen, Wilhelm II reversed the original concept and built his part of the castle on the site of the outer bailey. By 1358, a residential building was erected with Germany's oldest casemates, oriented to the east and south. The three-story, semicircular residential building features column constructions and architectural details suggesting Syrian Crusader castles. In 1479, the castle passed to Hesse through inheritance and served as a Hessian fortress for a long time.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=932
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: 50.1585, 7.7600