Datum održavanja: 01.01.1970.

The city of Sirmium, concealed beneath the streets of the present day Sremska Mitrovica, was one of the metropolis of the Roman Empire and belonged to the largest metropolis for the time being . Sirmium, as a settlement dates back to the ancient Celtic times, and it was built 7,000 years ago. It is supposed that during the period before the Roman occupation it was the Illyrian-Celtic village and fortifications of the Sirmijenza tribes. The historian Matthias Corvinus wrote that the city was named by Sirm, the leader of the Illyrian tribe of Tribal.
Ancient history of Sirmium covers the period of about six centuries, following the splendor and downs, "the most powerful empire the world". Sirmium is mentioned for the first time in written sources at the end of the first century BC. Sirmium was built on the Sava River, on one of the early natural communications between Aquileia on the Adriatic Sea and the Danube. At the time of the Flavian dynasty Sirmium gained the highest urban rank, becoming Colonia Flavia Sirmiensium. The strongest urban expansion began at the end of the third century and lasted throughout partially the IV and V century. The greatest historian of the fourth century Amijan Marcelin named it" myriad, glorious mother of cities".
In the fourth century Sirmium already had a fully formed physiognomy of the lavish capital. In the center there was a large square - forum surrounded by public and administrative buildings. The imperial court with the basilica and the town hall, mint, granary, baths and temples also dominated nearby and were surrounded by numerous palaces adorned with stone facades, mosaics and frescoes as well as the workshops and metal and glass foundry, and a variety of shops and markets. Sirmijum had a theater, an amphitheater and a large racetrack by the imperial palace. Famous gladiators gave performances in the arena, and in the theater hosted actors from Greece as well. The famous Roman emperors Trajan Decius, Aurelian, Probus and Maximianus were born, who were not only good fighters but also versatile builders.
The final fall of the ancient city of Sirmium into the hands of Avars in 582 marked the symbolic beginning of the end of history of the city.