Sylvester was pope from 314 to 335, the year after Constantine issued the Edict of Milan, which made Christianity the official religion of the Roman Empire. He is supposed to have baptised Constantine, who became the first Christian emperor. In fact, Constantine was baptised only on his deathbed, after Sylvester's death in 335. The Baptism of Constantine by Sylvester has, however, sometimes been depicted.
Sylvester, as pope, received from Constantine the gift of the Lateran Palace in Rome, which became the papal residence.
He is generally depicted with a chained dragon, the symbol of the fallen pagan religions.