The remains of the roman Castle can be visited
Roman Castle Kleiner Feldberg
The Roman Fort Kleiner Feldberg, also known as Feldbergkastell, is an ancient structure situated at an elevation of approximately 699 meters on the northern slope of the Kleiner Feldberg in the Taunus region. It was once the highest-lying fort along the entire Upper Germanic-Rhaetian Limes and served to secure an important pass.
History+
The fort was constructed around 150 AD, as indicated by small finds and dendrochronological dating. It housed a unit of approximately 160 men, the Exploratio Halicanensium, a partially mounted reconnaissance unit likely originating from Halicanum in Pannonia. Their primary task was to monitor the nearby Feldberg Pass. The site was strategically located near the Weil spring to ensure water supply. A trade route passed directly through the fort, allowing control over traffic.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:FeldbergKastellPortaDecumanaRestauriert.JPG
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: 50.2272, 8.4447