John Ray tells the story of the building of Alexandria dominated by the towering Pharos and explores the technology which underlay its workings. It was only one of the achievements of that city, the New York of the ancient Mediterranean, with its museum and greatlibrary; its slot machines and the health service for Greeks only; the mathematician Eratosthenes calculating the circumference of the world and Ptolemy mapping it. The Pharos and its city still live in Cavafy, Forster and Lawrence Durrell. There is a new library but no new lighthouse. But it survives in the word minaret – from the Arabic for lighthouse.