Sremska Mitrovica is a town with a very long continuity of life during which it has changed both its name and its phisiognomy several times: at first it was a wooden Illyrian-Celtic settlement, afterwards it was an antique city and metropolis, a medieval town with a variety of masters, an Oriental intrenched settlement with minarets, the headquarters of the Border Regiment, a crafts and commerce centre throughout the period of urban prosperity and, finally, a modern industrial town at the peak of modern history.
The Romans conquered Sirmium at the end of the first century BC. The city kept growing amazingly fast and in the first century AD the city got the highest rank of an urban settlement – it became Colonia Flavia Sirmiensium and was given an extrodinary military and strategic importance. War expeditions of the emperors such as Traian, Marcus Aurelius and Claudius II Ghoticus were prepared there. Since the middle of the third century, Sirmium had become the economic centre of the entire Pannonia, and therefore it gave the Empire a few great men. The emperors such as Decius Traianus, Aurelian, Probus and Maximilianus, all of them being Romanized native Illyrians, were born in the city or in this region.
In the period of Tetrarchy it was confirmed that Sirmium had an outstanding position within the Roman Empire and it became one of the four capitals of the Empire, a city with a royal palace, a hippodrome, a mint, an amphithetre, a theatre, a variety of workshops, public baths, temples, as well as with numerous public palaces and luxurious mansions.
Since 313, the Christian Church in Sirmium had overtaken a significant role being the centre of episcopacy. There had been fierce religious conflicts due to different religious doctrines and heresies for almost a century. Five synods were held in the city. The famous ‘formulas of Sirmium’ dealt with the issues of high importance for the entire Christian world. In the fifth century, the Hunns devastated the city and stopped its development. The Ostroghots and the Gepids had alternately ruled the city until Justin II annexed it to the Eastern Roman Empire. In the middle of the sixth century the Avars penetrated into Srem together with the first Slavic groups and they definitely seized and destroyed Sirmium in 582.
In the ninth century Srem belonged to Bulgaria and its role was becoming more and more important because, just after the Bulgarians had adopted Christianity, the Episcopacy was founded there. The Slavic educator Methodius was thought to have been the Episcope of Sirmium before he went to Moravia. Since the arrival of the Hungarians, the Byzantines and the Hungarians had alternately ruled Sirmium, until the Byzantine rule permanently vanished from this territory in 1180, and the formerly glorious city was left in ruins. Only the restored Monastery of Saint Demetrius with the fortress remained. The new settlement which was built by the city walls was named Dmitrovica, after the monastery, in the thirteenth century (in Latin ‘Civitas Sancti Demetri’, in Hungarian ‘Szava Szent-Demeter’).
The Hungarian settlers fled from the invading Turks towards their homeland, and the Serbs continued settling down, so Srem became a Serbian region during a single century, and despot Stefan Lazarević acquired Mitrovica together with some other estates. After 1529, Srem finally became part of the Turkish Empire. In a few decades, the devastated Mitrovica turned into Dimitrovica-Seher, an Oriental town with a large bazaar, which became the economic and administrative centre of Srem. After the peace treaty in Požarevac, the town was liberated from the Turks and annexed to the Habsburg Monarchy. In the mid-eighteenth century the Ninth Petrovaradin Border Regiment was formed with its headquarters in Mitrovica. The Border Command ordered about thirty buildings to be built for the headquarters of the regiment.