Vestibule Mosaic of Constantine and Justinian

Everone when visits Hagia Sophia as a tourist today enters from the vestibule on the south side of the building.  Here was discovered a beautiful mosaic.

Russian Painter - Mikhail Vasilievich Nesterov

Nesterov was one of Empress Alexandra's favorite painters, his picture of the Annuciation hung in the Mauve Room.  He worked for Grand Duchess Elizabeth in her Martha and Mary convent in Moscow.  Here's a bio.