Marian cycle in the oratory of John VII. Vatican, Biblioteca Apostolica, Barb. lat. 2732, fols. 76v–77r (detail)
Mosaic of Mary in Chiesa di San Marco, Florence
The image of Mary crowned as Queen (or Empress) of heaven is usually known by the Latin phrase "Maria regina".
Mary is shown wearing Imperial dress and a crown. Until the beginning of the 8th century, such images were relatively unknown in Rome. However they were common in Constantinople.
One of the earliest examples was the mosaic of the Virgin orans. It used to be in the funerary chapel of Pope John VII (705-707) in Old St Peter's Constantinian Basilica in Rome.
In 1605 Pope Paul V ordered the east end of old St. Peter’s nave, the last section of the early Christian basilica still standing, destroyed . Included was a the oratory of Pope John VII (705–707), on the east end of the church’s outermost north aisle
Pope Paul V provided for the preservation of “memoriae”from the old church, as well as for detailed documentation of the structure . The job of implementing these provisions fell to Giacomo Grimaldi,
His drawings and descriptions provide some of the most detailed information known about the early Christian basilica.
The head of Mary with crown survived the demolition of Old St Peter's. Today it is over an altar in the church of San Marco in Florence.
John VII had a strong devotion to Mary
The large central panel on the east wall of the Oratory presented “John, the unworthy bishop and servant of the holy mother of God,”. The Virgin is depicted in the surrounding narrative scenes,of the Annunciation, Visitation, Nativity, and Adoration of the Magi.
The increased incidence of this type of imagery at this particular time in Rome has been linked to a concurrent influx of Greek-speaking immigrants
John was of Greek nationality. John’s father, Plato, was cura palatii urbis Romae, or curator of the Palatine Hill. This makes John the first pope to be the son of a Byzantine official
"[T]he Second Ecumenical Council of Nicaea (787)..[put] an end to the well known controversy about the cult of sacred images, this Council defined that, according to the teaching of the holy Fathers and the universal tradition of the Church, there could be exposed for the veneration of the faithful, together with the Cross, also images of the Mother of God, of the angels and of the saints, in churches and houses and at the roadside Images of the Virgin have a place of honor in churches and houses.
In them Mary is represented in a number of ways: as the throne of God carrying the Lord and giving him to humanity (Theotokos); as the way that leads to Christ and manifests him (Hodegetria); as a praying figure in an attitude of intercession and as a sign of the divine presence on the journey of the faithful until the day of the Lord (Deesis); as the protectress who stretches out her mantle over the peoples (Pokrov), or as the merciful Virgin of tenderness (Eleousa).
She is usually represented with her Son, the child Jesus, in her arms: it is the relationship with the Son which glorifies the Mother. Sometimes she embraces him with tenderness (Glykophilousa); at other times she is a hieratic figure, apparently rapt in contemplation of him who is the Lord of history (cf. Rev. 5:9-14)"
(Pope John Paul II: Redemptoris Mater, paragraph 33----- 25th March 1987)