The first stroke against Athens was dealt by the Herulians, barbarian invaders of Germanic speech who sacked the city in AD 267 and left it in ruins. Even after the catastrophy of AD 267, however, Athens remained an important center for philosophical (Neoplatonic) studies. The stroke which definitely finished her, the coup de grace, was delivered not by a barbarian but by a Christian: the Emperor Justinian (AD 527-565) who repudiated the pagan past of the Greco-Roman world, and closed the schools of philosophy, and in the Greek world, the light of Athens was completely obscured by Constantinople, the capital of the East Roman (or Byzantine) empire. The dark age of Athens, beginning in the 6th century, became even darker when in the 15th century Greece itself was conquered by the Ottoman Turks and the Athenian Parthenon which had already been converted into a Christian church was turned into a Turkish mosque.