The Theotòkos is a typical Byzantine icon painted on gilt board. The Virgin, with big eyes, holds the blessing Child. The author is unknown. Probably it is one of the many icons that the Greek monks reproduced imitating those ones destroyed in the East by the fury of the iconoclasts.

In 1140 Tolomeo II, count of Tuscolo, deprived the Church of many precious objects among which was maybe the icon of the Virgin. A well-grounded tradition says that this icon was worshipped for many years in a Church in Tuscolo. In 1191 Tuscolo was destroyed by the Romans and the icon was brought to Rome. In 1230 it was given back by Pope Gregory XI to the monks of the Abbey and solemnly enthroned.

For a long time it was placed on the side-altar. In the second half of the seventeenth century it was placed on the main altar, a work of Bernini. In 1687 the Vatican Chapter ordained its coronation.

This consecrated icon has granted many graces from heaven and it has gathered a multitude of faithful and pilgrims, among which were many saints and popes. Among them, was Pope Pius IX who often came to pray before its altar; Pope John XXIII came in 1960 and Pope Paul VI on the 19th of August 1963 made a sad appeal to the separated brothers of the christian East. Pope John Paul II visited the Monastery twice (on 1979 and 1987).

The crowd of pilgrims on the Feast Day of the Mother of God has been a huge one ever since and from the beginning tents had to be pitched and food stands raised to meet the needs of the pilgrims. Thus it was from Medieval times that the two Fairs of Grottaferrata began: one on March 25, Annunciation Day, the other on September 8, the Nativity of Mary. The Annunciation Day Fair was declared a National Fair for agricultural machinery in 1966.