Sremska Mitrovica is one of the oldest cities in Europe. Archaeologists have found a trace of organized human life dating from the 5000 BC onwards. Ionian jewellery dating to 500BC was excavated in the city. When the Romans conquered the city in the 1st century BC, Sirmium already was a settlement with a long tradition.
In the 1st century, Sirmium gained a status of a colony of the citizens of Rome, and became a very important military and strategic location in Pannonia province. The war expeditions of Roman emperors Traian, Marcus Aurelius, and Claudius II, were prepared in Sirmium.