Three cities dominated the ancient world: Athens, Rome and a third, now almost forgotten. It lies hidden beneath the waters of the Mediterranean and a sprawling modern metropolis. Alexandria was a city built on a dream; a place with a very modern mindset, where - as with the worldwide web - one man had a vision that all knowledge on earth could be stored in one place. Bettany Hughes goes in search of this lost civilisation, revealing the story of a city founded out of the desert by Alexander the Great in 331 BC to become the world's first global centre of culture, into which wealth and knowledge poured from across the world. Until its decline in the fourth and fifth Centuries AD, Alexandria became a crucible of learning; Hughes uncovers the incredible discoveries and the technical achievements of this culture. The film's cast of characters reads like a list of the greatest figures of ancient times: political figures like Alexander the Great, Julius Caesar and Cleopatra, and intellectuals including female mathematician, astronomer and philosopher Hypatia, Euclid, Archimedes, Eratosthenes and Ptolemy. At last, after 1,500 years squashed under a modern metropolis, new clues are emerging from the earth to the real nature of this grand experiment in human civilisation.