Hagia Sophia is a former Greek Orthodox Christian patriarchal basilica (church), later an Ottoman imperial mosque and now a museum in Istanbul. The first church on the site was known as the "Μεγάλη Ἐκκλησία" ("Great Church"), or in Latin "Magna Ecclesia", because of its larger dimensions in comparison to the contemporary churches in the City.
- Location: Istanbul, Turkey
- Construction started: 532
- Completed: 537
- History:
*Christian Cathedral (537–1054)
*Greek Orthodox Cathedral (1054–1204)
*Roman Catholic Cathedral (1204–1261)
*Greek Orthodox Cathedral (1261–1453)
*Imperial Mosque (1453–1931)
*Museum (1935–present)