Noviodunum ad Istrum was a Roman city that developed around the legionary fortress and naval port near the present town of Isaccea.

The strategic position of the fort allowed the Romans to supervise and control the border of the entire Moesian Limes along this section of the Danube.

It became the main port of Classis Flavia Moesica[5] and a military centre of the region under Domitian, and after the conquest of Dacia by Trajan.

Between 434 and 441 the city with its naval base was occupied by the Huns and then went back under Roman rule to be part of the Byzantine Empire.

[11] A second civil settlement of at least 7 ha depending on the military garrison would be inside the three huge earth ramparts.