Emperor Justinian I commissioned Hagia Sophia in Constantinople after the Nika riots of 532.
The earlier church on the site was destroyed during the uprising, so Justinian ordered a vastly more ambitious replacement. Construction began in 532 and the new church was dedicated in 537, an exceptionally rapid project for its scale.
Justinian chose the mathematician Anthemius of Tralles and the physicist Isidore of Miletus as architects. Their design combined a huge central dome with longitudinal basilica planning, creating an interior that became a defining achievement of Byzantine architecture.
Hagia Sophia served as Constantinople’s imperial cathedral for centuries. It became a mosque after the Ottoman conquest in 1453, a museum in 1935, and a mosque again in 2020. Justinian is sometimes confused with Constantine, who founded Constantinople but did not commission the surviving building.