The subject of this study is how the historical figure, Mary, the mother of Jesus, came to play such a vital role in the cultural and religious life of Constantinople in late antiquity. More specifically, how she is transformed from a humble Jewish maiden of first-century Palestine into a divine figure, intercessor, and the supernatural protector of the city of Constantinople is the crucial question. Mary’s apotheosis must be seen in the context of the religious culture of the Mediterranean world, especially during the critical period after 325 when Constantine makes Christianity the official religion of the Roman empire. For with this event two very different religious cultures, pagan and Christian, were united at the most fundamental level: the level of civic religion.