Argentovaria, also known as Ödenburg, is the collective term for a late Roman military installation and a civilian settlement in the area of Biesheim in Elsass (Canton Neuf-Brisach, Arrondissement Colmar-Ribeauvillé, Communauté de communes du Pays de Brisach).
The ancient sites of Biesheim-Kunheim and Ödenburg-Altkirch owe their importance to their position at an important crossing over the Rhine. In the 1st and the 4th centuries AD the area was dominated by the military, but in the 2nd and 3rd centuries AD, the civilian settlement came to the fore. During the great barbarian invasions in the 4th and 5th centuries AD Argentovaria was probably part of a chain of forts that also included the fortifications on the right bank of the Rhine on the Münsterberg in Breisach and on the Sponeck in Sasbach am Kaiserstuhl.
The late Roman castrum was probably one of the numerous border fortresses built under Emperor Valentinian I in the final phase of Roman rule over the Rhine provinces, but only briefly occupied. It was part of the chain of forts of the Danube-Iller-Rhine Limes in the section of the Maxima Sequanorum province. The fort was probably occupied by Roman troops from the 4th to the 5th century AD who were responsible for security and surveillance tasks along the Rhine border.
Name
The ancient name of the civil settlement and the fort are known to us from the second century geographer Claudius Ptolemy and from the Tabula Peutingeriana. Inscriptions supporting this name have not yet been discovered. Around the year 150 Ptolemy referred to the civil settlement of Argentovaria as the "second polis" of the Celtic Rauraci people after Augusta Raurica. The current name "Altkirch" (popularly "Kirchenbuckel") derives from a medieval church which, together with its cemetery has been identified west of the south gate of the fort.
Location
Biesheim is about halfway between Basel and Straßburg, north of Neuf-Brisach and exactly opposite the Kaiserstuhl mountain range. The mountain ranges of the Vosges and the Black Forest, in connection with the strongly meandering Rhine, were considerable obstacles to travel, and to this day only allow east–west passage in a few places. The late antique fort is located on the left bank of the Rhine, a little northwest of the fort at Breisach. The archaeological sites are north of Biesheim. Maps from the 16th and 17th centuries show a place called Edenburg, Oedenburg or Oedenburgheim, which was destroyed in the Thirty Years' War and not rebuilt afterwards. The first wood and earth fort that can be identified here stood on an island on the Rhine, which offered good natural protection. The area of the later fort is currently used intensively for agriculture, and is only recognizable by the relief of the terrain. The fortification was located directly east of the Limes road (via puplica), close to the subsidence of what was then the banks of the Rhine, and was therefore easily accessible by land and also by ship. The findings indicated that as a result, the fort was hit by floods more frequently. Today only the Riedgraben Canal passes here, a sparse remnant of the ancient river bed. The border line between the two Rhine provinces Germania Prima and Maxima Sequanorum ran north of the Kaiserstuhl mountains. Along this line a road from Biesheim-Oedenburg that crossed the Vosges and Divodurum (Metz) and reached the bank of the Rhine. Here it subsequently crossed with the Limes road on the left bank of the Rhine, running from north to south. The fort probably had a strong relationship to this road network.