The architects Isidorus of Miletus and Anthemius of Tralles are known for having built the monumental church of Hagia Sophia in Constantinople (now Istanbul), after it burned down for a second time in 532 C.E. Employed by the Byzantine emperor Justinian I, the two architects, highly skilled in mechanics and mathematics, oversaw the construction of the church in just six years. Hagia Sophia’s vast 105-foot dome is pierced with windows, giving the impression that it floats on air. After the Turkish conquest of Constantinople in 1453, the church was repurposed as a mosque, minarets and a mihrab were added, and giant disks bearing Islamic calligraphy were installed on the building’s walls.