information:extraction
Apse mosaics

The mosaic in the semi-dome above the apse at the east end shows Mary, mother of Jesus holding the Christ Child and seated on a jewelled thokos backless throne. Since its rediscovery after a period of concealment in the Ottoman era, it "has become one of the foremost monuments of Byzantium". The infant Jesus's garment is depicted with golden tesserae.

Guillaume-Joseph Grelot, who had travelled to Constantinople, in 1672 engraved and in 1680 published in Paris an image of the interior of Hagia Sophia which shows the apse mosaic indistinctly. Together with a picture by Cornelius Loos drawn in 1710, these images are early attestations of the mosiac before it was covered towards the end of the 18th century. The mosaic of the Virgin and Child was rediscovered during the restorations of the Fossati brothers in 1847–1848 and revealed by the restoration of Thomas Whittemore in 1935–1939. It was studied again in 1964 with the aid of scaffolding.

It is not known when this mosaic was installed. According to Cyril Mango, the mosaic is "a curious reflection on how little we know about Byzantine art". The work is generally believed to date from after the end of Byzantine Iconoclasm and usually dated to the patriarchate of Photius I (r. 858–867, 877–886) and the time of the emperors Michael III (r. 842–867) and Basil I (r. 867–886). Most specifically, the mosaic has been connected with a surviving homily known to have been written and delivered by Photius in the cathedral on 29 March 867.

Other scholars have favoured earlier or later dates for the present mosaic or its composition. Nikolaos Oikonomides pointed out that Photius's homily refers to a standing portrait of the Theotokos – a Hodegetria – while the present mosaic shows her seated. Likewise, a biography of the patriarch Isidore I (r. 1347–1350) by his successor Philotheus I (r. 1353–1354, 1364–1376) composed before 1363 describes Isidore seeing a standing image of the Virgin at Epiphany in 1347. Serious damage was done to the building by earthquakes in the 14th century, and it is possible that a standing image of the Virgin that existed in Photius's time was lost in the earthquake of 1346, in which the eastern end of Hagia Sophia was partly destroyed. This interpretation supposes that the present mosaic of the Virgin and Child enthroned is of the late 14th century, a time in which, beginning with Nilus of Constantinople (r. 1380–1388), the patriarchs of Constantinople began to have official seals depicting the Theotokos enthroned on a thokos.

Still other scholars have proposed an earlier date than the later 9th century. According to George Galavaris, the mosaic seen by Photius was a Hodegetria portrait which after the earthquake of 989 was replaced by the present image not later than the early 11th century. According to Oikonomides however, the image in fact dates to before the Triumph of Orthodoxy, having been completed c. 787–797, during the iconodule interlude between the First Iconoclast (726–787) and the Second Iconoclast (814–842) periods. Having been plastered over in the Second Iconoclasm, Oikonomides argues a new, standing image of the Virgin Hodegetria was created above the older mosaic in 867, which then fell off in the earthquakes of the 1340s and revealed again the late 8th-century image of the Virgin enthroned.

More recently, analysis of a hexaptych menologion icon panel from Saint Catherine's Monastery at Mount Sinai has determined that the panel, showing numerous scenes from the life of the Virgin and other theologically significant iconic representations, contains an image at the centre very similar to that in Hagia Sophia. The image is labelled in Greek merely as: Μήτηρ Θεοῦ, romanized: Mētēr Theou, lit. ' Mother of God ', but in the Georgian language the inscription reveals the image is labelled "of the semi-dome of Hagia Sophia". This image is therefore the oldest depiction of the apse mosaic known and demonstrates that the apse mosaic's appearance was similar to the present day mosaic in the late 11th or early 12th centuries, when the hexaptych was inscribed in Georgian by a Georgian monk, which rules out a 14th-century date for the mosaic.

The portraits of the archangels Gabriel and Michael (largely destroyed) in the bema of the arch also date from the 9th century. The mosaics are set against the original golden background of the 6th century. These mosaics were believed to be a reconstruction of the mosaics of the 6th century that were previously destroyed during the iconoclastic era by the Byzantines of that time, as represented in the inaugural sermon by the patriarch Photios. However, no record of figurative decoration of Hagia Sophia exists before this time.