The Greeks of the Classical and Hellenistic eras made seminal contributions to science and philosophy, laying the foundations of several western scientific traditions, such as astronomy, geography, historiography, mathematics, medicine, philosophy and political science. The scholarly tradition of the Greek academies was maintained during Roman times with several academic institutions in Constantinople, Antioch, Alexandria and other centers of Greek learning, while Byzantine science was essentially a continuation of classical science. Greeks have a long tradition of valuing and investing in "paideia" (education). "Paideia" was one of the highest societal values in the Greek and Hellenistic world while the first European institution described as a university was founded in 5th century Constantinople and operated in various incarnations until the city's fall to the Ottomans in 1453. The University of Constantinople was Christian Europe's first secular institution of higher learning since no theological subjects were taught, and considering the original meaning of the world university as a corporation of students, the world's first university as well.