Sirmium was an ancient city located in present-day Sremska Mitrovica, Serbia. It served as a significant urban center in the Roman Empire, particularly during the 3rd and 4th centuries AD. Sirmium was known for its strategic position along trade routes and its role as a military base. It was also one of the four capitals of the Roman Empire during the Tetrarchy. The city was famous for its impressive architecture, including basilicas, palaces, and amphitheaters. Sirmium was the birthplace of several Roman emperors, such as Marcus Aurelius Probus and Maximianus. Today, the archaeological remains of Sirmium provide valuable insights into Roman urban life and culture.