Saints Constantine and Helena were significant figures in early Christianity. Constantine, also known as Constantine the Great, was the first Roman emperor to convert to Christianity. He ruled from 306 to 337 AD and played a crucial role in the Edict of Milan, which granted religious tolerance to Christians in the Roman Empire. Helena, Constantine's mother, is revered for her strong faith and dedication to Christianity. She is credited with finding the True Cross, the cross upon which Jesus was crucified, during her pilgrimage to Jerusalem. Both saints are celebrated for their contributions to the spread of Christianity and are commemorated on May 21.