Isidore of Miletus is known to history as one of two architects who designed the sixth century rebuilding of the Hagia Sophia in Constantinople (today’s Istanbul). The second church built on the same site was destroyed during the Nika riots of 532. The Emperor Justinian had just embarked on an enormous building plan at the time. He hired Isidore and Anthemius of Tralles to build a third church that would last for many ages. Justinian was a man of big ideas who insisted upon making big statements concerning his own personal power and that of what was then the Roman Empire. The architects did not let him down. Isidore helped to engineer a structure that still stands today. Justinian had materials brought from all over the empire: porphyry from Egypt, green marble from Thessaly, black stone from the Bosporus region and yellow stone from Syria. More than ten thousand people were employed during the construction. When it was completed the new church was immediately recognized as a genius work of architecture. Isidore and his partner may have relied on the theories of Heron of Alexandria. The church is supported by an enormous dome covering an equally large space. Later visitors to Hagia Sophia described standing in the church and looking up at the dome, which was said to appear to be as suspended upon a golden chain. Russian visitors in the late tenth century claimed they felt as though they were in heaven standing beneath the dome.

Prior to taking the Hagia Sophia job, Isidore had a long career teaching physics in Alexandria, Egypt, and later at Constantinople. He was a prolific writer as well, focusing on the history and science of construction. He collected and publicized the writings of Eutocius, which were commentaries on the mathematics of Achimedes and Apollonius, which helped to revive interest in their works. Through his efforts, these important writings were preserved and passed down the generations. Isidore was also an able mathematician, to whom we owe the T-square, the string construction of a parabola, and possibly the apocryphal Book XV of Euclid’s Elements.