History of Alexandria Severus after temporary abolition by Augustus. Monumental buildings were erected in Alexandria through the third century BC. The Heptastadion connected Pharos with the city and the Lighthouse of Alexandria followed soon after, as did the Serapeum, all under Ptolemy I. The Museion was built under Ptolemy II; the Serapeum expanded by Ptolemy III Euergetes; and mausolea for Alexander and the Ptolemies built under Ptolemy IV. The Ptolemies fostered the development of the Library of Alexandria and associated Musaeum into a renowned center for Hellenistic learning. Luminaries associated with the Musaeum included the geometry and number-theorist Euclid; the astronomer Hipparchus; and
Library of Alexandria who had studied at the Library of Alexandria and their students continued to conduct research and write treatises, but most of them no longer did so in association with the Library of Alexandria. A diaspora of Alexandrian scholarship occurred, in which scholars dispersed first throughout the eastern Mediterranean and later throughout the western Mediterranean as well. Aristarchus's student Dionysius Thrax ( 170– 90 BC) established a school on the Greek island of Rhodes. Dionysius Thrax wrote the first book on Greek grammar, a succinct guide to speaking and writing clearly and effectively. This book remained the primary grammar textbook for