Roman Emperor. He was born into a military family in AD 271, and as a young man he served in the army under the Emperors Diocletian and Galerius. On the death of the Emperor Constantius in AD 306 he was proclaimed Augustus by the army in Britain, and immediately took up residence in the city of Augusta Treverotum (modern Trier) where he remained for the next six years. In AD 312 he became the sole ruler of the Western Empire after defeating his rival Maxentius in the Battle of the Milvian Bridge. He ended all persecution of Christians in his territory, but continued with his own worship of the pagan gods. The night before the Battle of the Milvian Bridge he is said to have been commanded in a dream to place the sign of Christ on his soldier's shields, and he attributed his victory to the Christian God and converted to Christianity. He was responsible for many great buildings in Rome, including the Arch of Constantine and the Basilica of Saint Peter, which he originally intended as his mausoleum. He also built the Church of the Holy Sepulchre in Jerusalem. In AD 316 he entered into open warfare with Licinius, the Emperor of the Eastern Empire, and eventually had him executed in AD 324, becoming the sole ruler of the Empire. He took an active role in religious affairs, and in AD 325 presided over what is now known as the First Ecumenical Council of the church, which formulated the Nicene Creed, affirming that the Father, Son and Holy Ghost are all one entity. In AD 324 he founded a new capital for the Empire at Constantinople, which became the center of power in the East, and later the capital of Byzantium. He also reformed the currency of the Empire, and introduced a new type of coin, the gold solidus, which remained the standard for several centuries. In the final years of his reign he appointed four Caesars as co-rulers, these were three of his sons and a nephew, but he left no clear indication as to who should be his successor. He died in AD 337, shortly after his formal baptism into Christianity.