Constantine the Great

Constantine I (27 February 272 – 22 May 337 AD) was a Roman emperor from 306 until he died. He was emperor for longer than any other emperor since Augustus, the first emperor. He was the first ruler of the Roman Empire to be a Christian. He made the old city Byzantium into a new, larger city: Constantinople (now Istanbul, Turkey). The city's name means "City of Constantine" in Greek. He was the son of the emperor Constantius I, and members of their Constantinian dynasty controlled the empire until 364.

Six years after Constantine said that he was emperor, he was fighting for control of Rome with Maxentius at the Battle of Milvian Bridge, a bridge over the Tiber River. When he saw a cross in the sky with the words Latin: in hoc signo vinces, lit. 'in this sign you shall conquer', he changed his deity from Apollo to Jesus and won the battle or war.