About the Roman history of the region
The southern Upper Rhine region is an old Roman arable land. During the reign of Gaius Julius Caesar the Rhine became the Roman imperial frontier. In the early 1st century the territories on the eastern bank of the river Rhine were secured by the Roman military. There were military bases in Riegel at the northern edge of the Kaiserstuhl and on the Limberg close to Sasbach. Consequently, the Upper Rhine region was incorporated into the Roman Empire and became densely populated by civilians.
Close to Grenzach, Auggen and Heitersheim Roman farms had been built first and later they were extended to enormous estates. Numerous estates in the area of the Roman town Augusta Raurica and along the southern Upper Rhine, located in Wyhlen, Rheinfelden-Nollingen, Lörrach-Brombach, Fischingen, Efringen-Kirchen and in Müllheim, as well as larger colonies such as those in Bad Krozingen show evidence of the region’s prosperity which was also due to the fertile soil. Close to Bad Bellingen and Schliengen signs of Roman iron mining were found. A curative spring represented the origin for the settlement of Badenweiler. Subsequently, the Romans built up around this spring the biggest thermal spa on the right bank of the Rhine. At that time Riegel was an administrative centre. An important market basilica and further ruins of a Roman town were discovered there.
After having lost the territory of the Province Germania Superior on the right bank of the Rhine in the 3rd century, the Romans fortified the Rhine frontier again. In the 4th century they built Roman fortifications on the Rhine; for example the bridge castle near Wyhlen, the fort on the Münsterberg in Breisach and the fortlet in Jechtingen. This Danube-Iller-Rhine Limes, built in the late antiquity, represented the last Roman frontier in this region and it was in existence until the 5th century.