Was the first stone fortress built in the Roman Dacia. One scene on Traian’s Column which presents the inauguration of the bridge (in the spring of 105) reveals the Roman castrum of Drobeta already built. It is a small size fortification (137,50 m x 123 m), which comprises approximately 2 hectares of land.

It was a Roman castrum for auxiliary units, where Cohors III Campestris, Cohors I Antiochensium, Cohors I Cretum, Cohors I Sagittariorum and others were successively stationed. As for the interior structure, the Roman Castrum of Drobeta respects the building rules of a Roman Castrum with gates, interior roads, depots, hospital, soldiers’ rooms, praetorium and others. Its main gate is however facing south, the Roman castrum’s main role being of defending the northern bridge head of Drobeta.

The Roman Castrum, as well as the ancient town Drobeta, was not abandoned in 274. The present ruins display the cross shape obtained after the organisation of the interior space which took place during the retreat in the time of Constantine the Great (306-337).

The last Roman Castrum’s restoration dates from the time of emperor Justinian the Ist (527-565). During that period, from the dwellings around the Roman Castrum was born the ancient town called Drobeta.