Viminacium, a major city of the Roman province of Moesia, and the capital of Moesia Superior was situated 20 km east to the present centre, in the area of "Stari Kostolac" (Old Kostolac). Viminacium was the base camp of Legio VII "Claudia", and hosted for some time the IV "Flavia Felix". It was destroyed in 440 by the Huns, but rebuilt by Justinian I. During Maurice's Balkan campaigns, Viminacium saw destruction by the Avars and Slavs in 584 and a crushing defeat of Avar forces on the northern Danube bank in 599, destroying Avar reputation for invincibility.