Emperor Constantine the Great, the first Christian emperor in Ancient Rome
Constantine (the Great) was the first Christian emperor. He made a great many changes. In AD 313, by the Edict of Milan, he made Christianity legal. People could worship without fear of persecution. Under his leadership, Christians could no longer be arrested just for being Christian. After a fairly short period of time, Christianity became the dominate religion of Rome. After that, it became the law that you must be Christian to be a citizen of Rome.
He took the treasures from the temples in Rome and used this wealth to pay for the construction of new Christian churches. He outlawed gladiator contests. He reorganized the army by disbanding the Praetorian Guard, the guard who had held strong influence over the empire for so long. His taxation reforms just about broke everybody. Those who lived in the city of Rome had to pay their taxes in gold or silver. This tax was levied every four years. If you didnít pay, you were beaten and tortured. People sold their children into slavery to pay their taxes.
Constantine was a hard, vain, ruthless man, with a horrible temper. He had his own son executed without any proof of guilt.
He is famous building the city that carried his name Ė Constantinople. (This name was later changed to Istanbul.) He decided that Rome was too riddled with crime and poverty to worry about any more. He moved to the Eastern Roman Empire, and used tax monies from Rome to build his new capital. He was careful about it. He announced that the senate in Constantinople was of a lower rank than the Senate in Rome, but he clearly intended that his new capital would someday replace Rome. He died of natural causes in AD 337.