Sirmium

Sirmium was an ancient Roman city at the site of present-day Sremska Mitrovica in northern Serbia, on the Sava River near its confluence with the Danube. It developed into a major urban center in the province of Pannonia and served as a key military and administrative hub on the Danubian frontier.

In the late 3rd and early 4th centuries, Sirmium was among the empire’s principal seats under Diocletian’s Tetrarchy and is commonly listed as one of the four imperial capitals, alongside Mediolanum, Nicomedia, and Augusta Treverorum. The city saw extensive building activity and minted coins during the late empire, reflecting its regional significance.

After the decline of the Western Empire, Sirmium faced invasions and population shifts in the 5th century. Urban life waned, and the site was gradually eclipsed by new settlements in the medieval period.

Today the archaeological locality yields evidence of its urban layout, public buildings, and late antique life. The site is an important source for Roman provincial administration and late antique history in the Balkans, and the modern town of Sremska Mitrovica preserves the name and legacy of Sirmium.