The oldest surviving icon of the Annunciation is found in the Catacomb of Priscilla on the Via Salaria in Rome, Italy, and dates from the second half of the second century A.D. Priscilla is thought to have been a well-to-do Roman who converted to Christianity and was martyred. These Christian catacombs, along with many others found surrounding Rome, are a treasury of early Christian iconography.
One difference between this depiction of the Annunciation and later icons is that the Mother of God is shown with her head uncovered. In Rome, young virginal maidens would always have their heads uncovered, and so the imagery is in keeping with the Christian beliefs regarding Mary, the Mother of Jesus Christ. The veil worn in the East would come to dominate iconography of the Mother of God in later centuries.
Other than this difference, it is remarkable how similar this image is to the established iconography of the Annunciation: Mary seated in a high-backed chair, the Archangel Gabriel stood, robed simply, with bare feet, and arm raised to signify he is speaking:
Rejoice, O Full of Grace, the Lord is with You!
History and Development of the Annunciation in Iconography (beginning with the Catacombs of Priscilla)