The University of Constantinople (presumably created by Constantine ca 330 AD) was reorganized by Theodosius II in 425, fell on hard times around 600, was briefly closed in 726, and was recreated in the reign of Michael III, ca 860 AD, when it again became a brilliant cultural center. It had faculties of law, medicine, philosophy, mathematics, astronomy, and rhetoric. Its fame spread far beyonds the boundaries of the empire. The graduates of the University filled the positions of the civil service.

Its first director in this incarnation was Leo the Mathematician. His fame attracted many students, Christian and Muslim, to his lectures. Originally a private teacher, one of his students was taken prisoner by the Arabs. This student, hearing that Caliph al-Ma'mun was interested in geometry, volunteered to discuss it with the Caliph and his geometers. They were so impressed that they invited Leo to Baghdad to teach. When Emperor Theophilus found this out he made Leo a professor at the University, and then, director, ca 800 AD.

Michael Psellus was the son of a literate, middle-class woman working in the civil service. He combined Platonic scholarship and diplomacy in an unusual life at court. He created a Platonic Academy at Constantinople, which survived until the Turkish defeat in 1453. During the waning years after 1300, many scholars migrated to Italy. One of these was George Gemistos Pletho, who accompanied the Partriarch to the Council of Florence in 1438, carrying a treasure of Greek manuscripts. As Byzantium faded, the Italian Renaissance rose in its place.