It is an ancient town on the area of present Srеmska Мitrоvica, one of the four capitals of the Roman Empire. It was founded probably by the Illyrians. When in the 1st century the Romans conquered Sirmiјum, there had already been a settlement with a developed social life.
Even seven Roman emperors were born in or around Sirmium. The town is the centre of the Lower Pannonia province, an occasional imperial place of residence, a bishopric seat and a powerful army camp – the frontier-men. It was promoted into a capital city at the time of emperor Galerius, and was considered the most beautiful and the wealthiest town in Illyricum. It lasted like this for several decades during the 4th century. The renowned historian of that time, Аmiаn Маrcеlin, called it the glorious and the large population mother of all cities. Sirmium was often attacked by various barbaric tribes, but the final destruction was done by the Ancient Avars in the early 6th century.
In the Middle Ages it was restored and dedicated to St Dimitrios, after whom it got its present name. At that time, Srеmskа Мitrоvicа was in an area under a dispute beteen the two empires – the Austrian and the Ottoman, and was populated mostly by the Serbs of the border. In the Ottoman times it was also populated by the Muslims. In the 20th century, it belonged to Austro-Hungary, to the Kingdom of Serbs, Croats and Slovenes, to the Danube Dukedom of the Kingdom of Yugoslavia, to the Independent State of Croatia, the Socialist, then the Federal Republic of Yugoslavia and, finally, to Serbia.
In Sirmium, there are the remains of the discovered earliest Christian church in Serbia.
The investigations started in the early 20th century revealed a large portion of a settlement with its public buildings. There used to be two bridges. There was also an elaborate waterworks, supplied from the Fruška Gоra sources. At that time, the town used to have much more mounds, small lakes and ponds.