According to reports done by 19th century renovators, the Islamic calligraphy on the dome hides a large mosaic of Jesus as "Master of the World."
One of several medallions inscribed with the name of Allah, the Prophet Mohammed, the first four caliphs and the two grandchildren of Mohammed.
The face of one of the church's four seraphim, covered more than 500 years ago and unveiled again for the first time in 2009.
When the building became a mosque, the Ottomans tried to cover the crosses, which can still be seen here.
Purification urns from the city of Pergamon, called "the place where Satan dwells" in Revelation. Can you spot the 700 Club host snapping a picture?
The main doors of the Hagia Sophia. You can see the traces of what used to be a cross; the Ottomans turned it into an arrow.
Mosaic of the Virgin Mary with two emperors: Constantine I (r) offering the city of Constantinople to Mary and Justinian (l) offering the Hagia Sophia.
The Virgin and Child.
The Deesis ("supplication"), which portrays the Virgin Mary and John the Baptist asking Christ to have compassion on humanity.
Details of Christ in the Deesis.