Completion of the Hagia Sophia

The Byzantine emperor Justinian I completed the Hagia Sophia in Constantinople in 537 CE, less than six years after construction began, following the destruction of an earlier basilica on the site during the Nika riots of 532. Designed by the Greek geometers Isidore of Miletus and Anthemius of Tralles, the building's vast central dome, roughly 31 meters in diameter and supported on pendentives rather than a continuous circular wall, was an engineering achievement without precedent and remained the world's largest cathedral for nearly a thousand years. Converted into a mosque after the Ottoman conquest of 1453, then a museum in 1935 and a mosque again in 2020, the building has stood at the center of both Byzantine and Ottoman architectural history and directly influenced later Ottoman mosque design.