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

The Roman fort Hönehaus, also known as the small fort Rehberg, is a former Roman military camp. It was part of the Upper Germanic-Raetian Limes and is a UNESCO World Heritage site. The site is located on the Rehberg in the Großer Wald near Hettingen, a district of Buchen in the Neckar-Odenwald district. The preserved foundations of the fort are now conserved and freely accessible to visitors.
History+
Research suggests that the small fort Hönehaus had a predecessor, which was abandoned after the construction of the Hönehaus. The fort, measuring approximately 39.5 x 46 meters, was probably built in the 3rd century and existed until the fall of the Limes around 259/260 AD. The surrounding wall was one to 1.1 meters wide and featured rounded corners as well as single-lane entrances on the west and east sides.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:HoenehausEingangW.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: 49.5429, 9.3875