Among the great urban centres of the Roman Empire, Alexandria yielded place only to the imperial capital itself.1 Constantinople overtook Alexandria by 400. But Antioch, fourth of the quartet of top cities as viewed from mid-fourth-century Rome,2 was less populous and served a less wealthy hinterland. A fortiori, second-rank places like Carthage or Ephesus. And while all shared an intensely Latin or Greek, in any case Mediterranean character, that of Ἀλεξάνδρεια ἡ πρὸς ἰγύπτωι/Alexandrea ad Aegyptum, ‘Alexandria next to Egypt’, was thrown into dramatic relief by contrast with the Nile valley’s exotic antiquities and gods. Visitors were fascinated by a promiscuous mingling of Greek with Egyptian styles even in the downtown areas.3 Although the Alexandria of its great founder and the poet Callimachus, of the astronomer Ptolemy and the theologian Origen, of the mathematician Hypatia and the philosopher John Philoponus was undeniably a citadel of Hellenism, much in its markets and even its schools hinted at other worlds, in Egypt but also far beyond. With its mid-seventh century conquest by the armies of Islam, Arabia finally re-orients Egypt, and Alexandria too, away from the Mediterranean. At this point ancient historians lose interest, even while recognizing certain continuities.4