Constantine the Great (about AD274-337), Roman emperor (306-37), the first Roman ruler to be converted to Christianity. He was the founder of Constantinople (present-day Istanbul), which remained the capital of the Eastern Roman (Byzantine) Empire until 1453.
Constantine the Great was born Flavius Valerius Constantinus at Nis, in what is now Serbia, son of the commander Constantius Chlorus.
In 312, on the eve of a battle against Maxentius, his rival in Italy, Constantine is reported to have dreamed that Christ appeared to him and told him to inscribe the first two letters of his name on the shields of his troops. The next day he is said to have seen a cross superimposed on the sun and the words "in this sign you will be the victor". Constantine then defeated Maxentius at the Battle of the Milvian Bridge, near Rome.
