This then is how he chose to begin his ministry.
From at least the 15th century, it was honored as a miraculous image, and it was later used by the Jesuits in particular to foster devotion to the Mother of God through the Sodality of Our Lady movement.
The Roman Breviary states, “After the Council of Ephesus (431) in which the Mother of Jesus was acclaimed as Mother of God, Pope Sixtus III erected at Rome on the Esquiline Hill, a basilica dedicated to the honor of the Holy Mother of God. It was afterward called Saint Mary Major and it is the oldest church in the West dedicated to the honor of the Blessed Virgin Mary.”
The Roman Pontifical gives an additional account, “The Liberian basilica, today called Saint Mary Major, was founded by Pope Liberius (352-366) and was restored and enlarged by Sixtus III. … Pope Liberius selected a venerated picture that hung in the pontifical oratory. It had allegedly been brought to Rome by St. Helena.”