In this city, Herophilus first suggested that blood circulates through the body, 1,700 years before Harvey. Here Aristarchus posited that the earth revolves around the sun, anticipating Copernicus by 1,800 years. Hipparchus measured the solar year to within 6½ minutes of accuracy, and Eratosthenes ascertained that the world was round 1,700 years before Columbus, and calculated the Earth's circumference with an error of only 50 miles. Archimedes studied hydraulics and gave us his eponymous screw, still used to irrigate Egypt today, and Euclid wrote his Elements of Geometry, to be the bane of schoolboys ever since.
Such were the scholars who inhabited the city founded by Alexander the Great in 331BC, which still bears his name. They were drawn by the greatest library in the world, repository of some 700,000 books in the form of scrolls, which contained, it was said, the sum of the world's knowledge. Yet today few visible signs remain of Alexandria's glory days, of the reign of the Ptolemies, the Greek dynasty established by Alexander. The great Pharos lighthouse, one of the seven wonders of the world, was destroyed by earthquakes in the Middle Ages; the Brucheion, the Ptolemaic royal quarter, has fallen into the sea. Most famously vanished is the great library of Alexandria, in circumstances that are still controversial.
The library was conceived by Ptolemy I around 295BC, and the blame for its destruction is most commonly laid at the door of Julius Caesar, who in 48BC accidentally set the building ablaze while attacking the fleet of Cleopatra's brother. What books remained, housed in the daughter library of the Temple of Serapis, were torched in the fourth century by the Christian zealots of the patriarch Theophilus. The catastrophe was symbolic as much as cultural. To replace such a lost treasure seemed an impossible dream.
On the shores of the Eastern Harbour, where under-water archaeologists currently seek the palace of Cleopatra and where, only last year, part of the ancient library was discovered, a 160m-wide shining disc seems to be rising, aslant like a silvery sun, out of the Mediterranean. It is the culmination of an idea mooted in 1974, which became reality when, in October 2002, the new Bibliotheca Alexandrina opened its doors.
The image of the sun, rising once again like a beacon of scholarship, is apt. "[The Bibliotheca Alexandrina] seeks nothing less than to recapture the spirit of the ancient library of Alexandria, centre of knowledge and of ecumenism of the ancient world," says Suzanne Mubarak, wife of President Hosni Mubarak and a driving force behind the project. "Borders disappear, minds meet and we all share in our common humanity in the best and most disinterested way."
The architectural competition for the new library, organised by Unesco in 1988, attracted 1400 entrants from 77 countries. It was won by a small Norwegian firm, Snhetta. Italian, British and Egyptian firms collaborated in the construction. International teams of experts were dragooned into working on different aspects of the complex, which includes museums and galleries, research institutes and auditoria - all connected beneath an open plaza studded with statuary and bisected by a slim pedestrian bridge. There is also a planetarium, a free-floating neon-lit sphere redolent of an orbiting planet to the library's sun. The whole is encompassed by a pool of water and a huge, circular granite wall of 6,000 un-polished slabs, carved with symbolic letters from 120 known scripts.
In the same spirit of co-operation, 30 countries and institutions, including Arab states, Unesco and computer companies, provided finance to the tune of $100m. This was not nearly enough, as it turned out. The project came in at a massive $220m, the cost of a Herculean feat of engineering that burrows 18 metres below ground, close to the the Mediterranean, and a dramatic design that spares no expense.
In a nod to the spirit of Islamic architecture, however, the library's lobby is modest. It offers no clue to what lies beyond the threshold: the largest open-access reading room in the world, the size of New York's Grand Central Station.
As you stand on the Callimachus balcony, a glass platform shaped like a ship's prow, named in honour of the ancient librarian who introduced cataloguing by subject and author, seven of the Library's 11 floors are seen to cascade below, as though seeking their level in the Mediterranean beyond. It is a lake of north American oak, contained within walls of shiny black Zimbabwean granite.
Supported by 98 concrete pillars suggesting lotus flowers, the glazed slanting roof, futuristically streaked with blue and green tubes of light, infuses the space with indirect natural light. Furniture is ergonomic, desks are inlaid with leather. There are specialist libraries for children, Braille and multimedia, and an internet archive of 10bn pages.
Despite the size, on each level the human scale is maintained. And, mindful of its predecessor's fate, a sophisticated system of fire curtains stand ready to drop, at the merest whiff of smoke.
Yet despite the high ideals of the venture, and the 1m visitors who have already admired this landmark building on tours conducted in six languages, the value of a library ultimately lies in the materials it contains. The director Dr Ismail Serageldin's dream that the library should foster a "dialogue of cultures to promote understanding and mutual enrichment" could prove difficult to realise in a country where freedom of expression remains a thorny issue. We are assured that censorship does not extend to the Bibliotheca Alexandrina. "Our policy," states the external relations department, "is that even if a book is banned or censored for the public, the library would still retain a copy or copies for research purposes."
Leaving aside what constitutes "research", of more immediate concern is the paucity of books. The metal stacks, which stand ready to accommodate 8m volumes, currently hold 350,000, with the cash-strapped Egyptian government depending largely on donations to fill its shelves. Faced with a similar dilemma 2,200 years ago, Ptolemy III came up with an ingenious strategy: every visitor to Alexandria had to yield up his books to scribes, who made copies. The copies were returned to the owners, while the originals found their way into the ancient library's cupboards. It was a solution of beautiful simplicity - but there are limits to how far the 21st-century library can dare to emulate its illustrious predecessor.
