In ancient Roman times it was called Viminatium (not to be confused with the Serbian province of Viminacium).
It became one of the primary settlements of Moesia, situated between Sirmium (modern Sremska Mitrovica) and Viminacium (modern Kostolac), both of which overshadowed Singidunum in significance, and just across the Sava River from Taurunum (modern Zemun) in Pannonia.
Via Militaris or Via Diagonalis was an ancient Roman road, starting from Singidunum (today the Serbian capital Belgrade), passing by Danube coast to Viminacium (mod. Požarevac), through Naissus (mod. Niš), Serdica (mod. Sofia), Philippopolis (mod. Plovdiv), Adrianopolis (mod. Edirne in Turkish Thrace), and reaching Constantinople (mod. Istanbul).