Ohrenbacher Schanze Earthwork

Three earthen ramparts roughly three meters high — two outer ones and an inner one — are surrounded by a ditch about 1.5 meters deep. At the center of the eastern short side lies the inward-drawn 'pincer gate,' oriented toward the praetorial front and containing many pieces of sandstone; at the east gate the ditch is interrupted. The interior, divided by a cross-ditch, holds the remains of a well, additionally protected by a surrounding rampart-and-ditch system. As early as 1813, Johann Friedrich Knapp gave the side lengths as 90 paces (nearly 66 m) and 80 paces (about 58.5 m); modern surveys of the terrain relief yield the somewhat larger figures noted above. This would make the site comparable to the forts of the Odenwald Limes, and in size even slightly larger than, for example, the Eulbach fort. Limes-type fortifications, which Knapp himself could no longer find and therefore doubted, cannot be verified on the plateau.

There is debate over whether the rampart served as an outpost of the Odenwald Limes to guard the ridge path, or as a work camp and sawmill site. It is assumed that Roman army logging details felled timber in the Odenwald for places such as Mogontiacum (modern Mainz) and floated it down the Main to the Rhine. In his 1995 dissertation, drawing on Bingemer, Theodor K. Kissel described the site as a timber-processing operation. Cited in support are four inscribed stones from the forts of Trennfurt, Obernburg, and Stockstadt, attributed to detachments of Legion XXII (Antoniniana) Primigenia Pia Fidelis stationed at Mogontiacum and dated to 206–214 AD. Because of its markedly rectangular shape, the Trennfurt fort is also considered a storage and loading site on the Main; in 1900, Wilhelm Conrady suspected a connecting route from there to the Hainhaus fort.