Serdica

Serdica lay in the central Balkans, where the centre of Sofia now stands. An anonymous fourth-century life of Constantine says that Galerius returned to Serdica, fell ill there with the disease that killed him, and died (Origo Constantini 3.8). The edict of toleration that he issued in his last weeks is therefore often called the Edict of Serdica. The text does not mention the edict, and neither Lactantius nor Eusebius, who preserve it, says where it was drawn up; its publication is recorded at Nicomedia. The same source places Constantine at Serdica a few years later, when he and Licinius agreed on the appointment of their sons as Caesars (Origo Constantini 5.19).