Constantine 57th Emperor of the Roman Empire. Constantine the Great (Latin: Flavius Valerius Aurelius Constantinus Augustus; 27 February c. 272 - 22 May 337), also known as Constantine I or Saint Constantine, was Roman Emperor from 306 to 337. Well known for being the first Roman emperor to convert to Christianity, Constantine and co-Emperor Licinius issued the Edict of Milan in 313, which proclaimed tolerance of all religions throughout the empire. Constantine defeated the emperors Maxentius and Licinius during civil wars. He also fought successfully against the Franks, Alamanni, Visigoths, and Sarmatians during his reign - even resettling parts of Dacia which had been abandoned during the previous century. Constantine built a new imperial residence at Byzantium, naming it New Rome. Howev