Constantine (also known with the ending "the Great"), lived from February 27, 272 to May 22, 337 A.D. He ruled as Emperor from 306 to 337 A.D. After his vision in Gaul in 312 A.D., whereby he is said to have become a Christian, Constantine became the first Roman ruler to treat favorably those who stated they were Christians.
History states that Constantine saw a flaming cross in the sky before an important battle with Maxentius (the then current Roman Emperor) and, taking it as a sign from God, went on to be victorious. There is, however, more to the story of what actually occurred.
"But exactly when Constantine had the vision of a sun cross, and what he believed it to mean, is unclear. What is well documented, however, is the vision's association with the evolved cult of the Sol Invictus (Sun worship), which had become quite popular among soldiers of the Roman army of that day . . .
"An obvious extension of the long established worship of the sun god, Baal, the phrase 'Sol Invictus' became a familiar battle cry, when soldiers in times of war appealed for the help of their invincible god, the sun (Baal). So for Constantine to say that in the conquest of his rival, Maxentius, he had a vision or dream from God . . . is, to say the least, highly suspicious" (Music of the Appointed Times by Dwight Blevins, page 22)
Constantine, through his Edict of Milan in 313 A.D., halted 246 years of state sponsored persecution against those who believed in Jesus Christ as the Messiah. He also subsequently stopped the bloody practice of slaves, criminals and even citizens of Rome doing battle with each other as entertainment for the masses.
Emperor Constantine, after coming to power, wanted to build a 'new Rome' somewhere in the east since that was where the Empire's economic life in the fourth century was centered. He eventually selected a spot on the Bosphorus called Byzantium.
One of the primary reasons Constantine selected Byzantium was that, like Rome itself, it was seated on seven hills. This made the 'New Rome' a city of Seven Hills just like its predecessor. After several years of construction, the city was officially made Constantine's capital in 330 A.D.
Byzantium was renamed Constantinople, in honor of the emperor, after his death. In 337 A.D., at the age of twenty-one, one of the sons of Constantine began to jointly rule the Empire. His failed invasion of Italy, however, cost him his life in 340 A.D.