Asking Mary's Prayers - When Did Christians begin to pray to Mary?

In the Gospel of Mary we got to see the tender affection that early Christians had for Mary. She was a very real person to them. They could relate to much of her life. They felt her pain at the death of her son on the cross.

The oldest known extant image of Mary comes from the catacomb of St. Priscilla, beneath Rome. The painting shows Mary with the infant Christ on her lap. A prophet stands beside them, pointing to the star above Mary's head, a sign of who she is. The way the painting looks, it feels as though we've just walked up on mother and son, perhaps interrupting a feeding.

In the same catacomb there is another fresco of Mary, from a slightly later period. This fresco shows Mary praying, her hands raised in the traditional orans position. She is facing us, challenging us.

The first image is dated to about AD 225. So, within the first three centuries of Christianity we know that Mary was revered enough to be placed on the walls of tombs, acting as a warrior for God in her devotion to Him through prayer.