MITROVICA (Hungarian, Mitrovicz; German, Mitrowitz), a town of Croatia-Slavonia, Hungary, situated on the river Save, in the county of Syrmia. Pop. (1900), 11,518. Mitrovica is on the railway from Agram, 170 m. W.N.W. to Belgrade, 38 m. E. by S. Roman remains have been discovered in its neighbourhood, and it occupies the site of Sirmium or Syrmium, the chief city of Lower Pannonia under Roman rule. The emperor Probus (232–282) was born and buried at Sirmium, where, according to some authorities, the emperor Marcus Aurelius (121–180) also died; but this is uncertain. In 351, 357 and 358, ecclesiastical councils of some importance met at Sirmium, which became an episcopal see about 305, and was united with the diocese of Bosnia in 1773. The city was sacked by the Huns in 441, and by the Turks, who destroyed all its ancient buildings, in 1396 and 1521.