St. Nicholas had a presence for many years in Hagia Sophia. A St. Nicholas mosaic was in the south tympanum. It disappeared long ago, though preserved by the Fossati brothers' drawing. The Saint Nicholas Passage wrapped around the curve of the apse on the outside of the building. The Chapel of Saint Nicholas was in the center of the Passage and best known for an icon of Christ. The Passage connected with a door in the Chapel of the Holy Well. The Chapel of Saint Nicholas was a first entry point for people seeking sanctuary in the church. Around 1200 it was reported that there was a tapestry of Saint Nicholas in the Passage. A building survey in 1320 led to buttresses being built to secure the building; they replaced the Saint Nicholas Passageway and Chapel.
Hagia Sophia was built by Justinian I in the 6th century. When Ottomans seized Constantinople, Hagia Sophia was converted into a mosque. This lasted from 1453-1935. In 1935 it was transformed into a museum and worship as a church or mosque was forbidden. It reverted to a Muslim mosque in 2018, with a decree in 2020 that any purpose other than being a mosque was annulled. Hagia Sophia remains open to visitors outside of prayer times.
