Castrum Noviodunum
Isaccea, Romania
Noviodunum ad Istrum was a Roman city that developed around the legionary fortress and naval port near the present town of Isaccea. It was in the Roman province of Moesia and was the headquarters of the Roman Danube fleet (Classis Flavia Moesica) located on the lower Danube and, from the 4th century AD, the headquarters of the Legio I Iovia (Scythica). From 46 AD the fortress was part of the Moesian Limes frontier defensive system on the Danube. In Late Antiquity the Imperial Road from Marcianopolis ended here. The fort of Aliobrix was located on the opposite bank of the Danube, which guarded a ford to Noviodunum.
Monument data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).