The remains of the roman Castle can be visited
Roman Castle Holzhausen

The Roman Fort of Holzhausen, a former Roman border fort of the Upper Germanic Limes, is one of the best-preserved Limes forts in Germany. It stands as an archaeological monument in the forests of Holzhausen an der Haide in Rhineland-Palatinate.
History+
The remote location of the fort long preserved its ruins from major interventions. It was not until the early 19th century, during the construction of the so-called Bäderstraße, that significant damage occurred as the fort walls were used as a quarry. A first detailed description of the site appeared in 1859. Between 1874 and 1882, Karl August von Cohausen conducted initial archaeological investigations. Extensive excavations then took place from 1897 to 1903 by the Imperial Limes Commission under Ludwig Pallat, followed by further excavations by Karl Nass in 1932.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:Holzhausen_an_der_Haide_Roemerkastell.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: 50.2149, 7.9475