The door, which is located at the west part of Hagia Sophia and on the same axis of the apse, is the imperial gate. As the name indicates, this door was used by the emperors and in the ceremonies related to them. The semi-circled space over the top is decorated with mosaics.
In the middle of the scene depicted, Jesus Christ is seen sitting on a throne over a ground made of gold. This throne, which is a replica of the Byzantine throne, is rnamented with pearls and precious stones. Christ Pantocrator (Ruler of the Universe) , while sitting on this throne, makes a sign of blessing with his right hand. He holds an open book in his left hand. In this open book, a quotation from the Bible of Saint John reads as follows in Greek: "Let peace and safety be with you. I am the peace and glorious light of the universe." Jesus here, whose feet are rested on a pedestal, has the expression and outlook similar to the statues of Asklepios, the god of good health of antiquity .
At the level of Christ's shoulders, we see that in the medallion on the right, Mary, Mother of Christ, and in the medallion on the left the Archangel Gabriel, the founder of the church, are portrayed. An emperor is seen lying prostrate in front of the throne. This is Leon VI, who reigned during the years between 886 and 912.
Above text and pictures are from the book titled "Hagia Sophia".
You can purchase "Hagia Sophia" book and other Turkey related books from Explore Turkey Bookstore.