Sisak is in a geostrategically important position, located in the southwestern part of the Pannonian plain. Segestica has been a settlement since prehistoric times, and it was in an interesting position for the Romans, which is why they tried to occupy it several times. Siscia is a neighboring settlement that corresponds simultaneously with Segesticaa, but it is not clarified when Segestika ceased to exist as a settlement, it is known that it was conquered in 35 BC. Kr. during Octavian's campaign. In the 1st century BC. Kr. after the Roman conquest there is no more mention of Segestika in the springs. Siscia became an important Roman center in Pannonia, along with Sirmium was the intersection of roads and contacts between West and East, the lobby of the entrance to the territory of Italy. It was of great importance during Baton's uprising, when it was fortified as an important military center. When the army withdrew from the city of Siscia it became an urban center, while in 71 it received the status of a colony of Colonia Flavia Siscia when the Roman Empire was ruled by Vespasian. A new flourishing occurs in the 4th century. then Diocletian rules. Conflict of Constantius II. with Magnentius it resulted in plunder and destruction and after that it no longer recovered. In the 3rd century, Emperor Gallienus founded a mint that operated until the 5th century and is significant even though the city had a developed craft infrastructure. There was also a Christian community in Siscia, and St. Quirinus as a martyr.