Constantinople Constantine Was the first Roman Emperor to become a Christian. During his reign, he prevented the persecution of Christians & helped to strengthen the early church Justinian's Code Justinian Sole ruler with complete authority Hapia Sophia Autocrat collection of Roman laws organized by the Byzantine emperor Justinian & later serving as a model for the Catholic Church & medieval monarchs

Shortly after the defeat of Maxentius, Constantine met Licinius at Mediolanum (modern Milan) to confirm a number of political and dynastic arrangements. A product of this meeting has become known as the Edict of Milan, which extended toleration to the Christians and restored any personal and corporate property that had been confiscated during the persecution. The extant copies of this decree are actually those posted by Licinius in the eastern parts of the empire. But Constantine went far beyond the joint policy agreed upon at Mediolanum. By 313 he had already donated to the bishop of Rome the imperial property of the Lateran, where a new cathedral, the Basilica Constantiniana (now San Giovanni in Laterano), soon rose. The church of St. Sebastian was also probably begun at this time, and it was in these early years of his reign that Constantine began issuing laws conveying upon the church and its clergy fiscal and legal privileges and immunities from civic burdens. As he said in a letter of 313 to the proconsul of Africa, the Christian clergy should not be distracted by secular offices from their religious duties “…for when they are free to render supreme service to the Divinity, it is evident that they confer great benefit upon the affairs of state.” In another such letter, directed to the bishop of Carthage, Constantine mentioned the Spanish bishop Hosius, who was important later in the reign as his adviser and possibly—since he may well have been with Constantine in Gaul before the campaign against Maxentius—instrumental in the conversion of the emperor.