I believe Constantine the Great's mother was Helen of the Cross, not someone named Sophia. After her divorce from Constatine's father, she devoted the rest of her life to religious pilgrimages. She was the founder of the Church of the Holy Sepulcher and the Church of the Nativity. According to some legends, she was the discoverer of the True Cross in Palestine.
Sophia refers to "Divine Wisdom" & the current Hagga Sophie's building is credited to Justinian.
Thanks. But do you remember the IHS part? It would be useful if you might.