Plan of Hagia Sophia
Hagia Sophia is a former patriarchal basilica, later a mosque, now a museum in Istanbul, Turkey. Famous in particular for its massive dome, it is considered the epitome of Byzantine architecture. It was the largest cathedral ever built in the world for nearly a thousand years, until the completion of the Seville Cathedral in 1520. The current building was originally constructed as a church between A.D. 532 and 537 on the orders of the Byzantine Emperor Justinian, and was in fact the third Church of the Holy Wisdom to occupy the site.
A. D. F. Hamlin College Histories of Art History of Architecture (New York, NY: Longmans, Green, and Co., 1915)