Remains of a small Roman castrum at the western part of the Limes Germanicus, today called castrum "Altes Jagdhaus" ("old hunting lodge"). The picture shows the overgrown remains of the Roman defensive wall and, in the middle, the base walls of a house from the 16th century, presumably a hunting lodge.
<a href="//commons.wikimedia.org/wiki/User:Johannes_Robalotoff" title="User:Johannes Robalotoff">Johannes Robalotoff</a>
CC BY-SA 3.0 de
<span class="int-own-work" lang="en">Own work</span>