The Main Limes, a part of the Upper German-Raetian Limes, formed a river boundary: between Seligenstadt and Miltenberg, the River Main, Lat. moenus, set the border. There are also references to "the wet border" and "the wet Limes".

History:
The forts Seligenstadt, Stockstadt, Niedernberg and Obernburg were founded around 105/106 AD under Emperor Trajan. The Main Limes first stopped at the mouth of the Mümling at Obernburg. The Limes continued at the ridge of the Odenwald (the older Odenwald Limes). In the hinterland, today's Dieburg was the main city of the "civitas Auderiensium".

Fort Hainstadt was abandoned under Hadrian (117-138 AD) and palisades were erected at the bank of the border. Street projects followed and watchtowers were built.

Towards the end of Antonius Pius' reign, at 159/160 AD, the Main border was extended through Wörth and Trennfurt to Miltenberg and the Limes was pushed southwards through Walldürn and Osterbürken to the border of the province of Raetia (southern Limes).

According to the division of the Reich-Limeskommission the Main Limes runs along Segment 6, northern part (Hainstadt to Wörth) and southern part (Trennfurt to Miltenberg), with a classification of older and younger Main borders.

As part of the Upper German-Raetian Limes, the c. 55 km long Main Limes was declared a UNESCO World Heritage Site in 2005.

Literature:
Steidl 2008, 32ff.