One story holds that the Library was seeded, so to speak, with Aristotle's own private collection, through one of his students, Demetrius. Another concerns how its collection grew so large. By decree of Ptolemy III of Egypt, all visitors to the city were required to surrender all books and scrolls in their possession; these writings were then swiftly copied by official scribes. The originals were put into the Library, and the copies were delivered to the previous owners. While encroaching on the rights of the traveler or merchant, it also helped to create a reservoir of books in the relatively new city.
The Library's contents were likely distributed over several buildings, with the main library either located directly attached to or close to the oldest building, the Museum, and a daughter library in the younger Serapeum, also a temple dedicated to the God Serapis[?]. Edward Parsons provides the following description of the main library based on the existing historical records:
One of the reasons so little is known about the Library is that it was probably burned to the ground centuries after its creation. All that is left of many of the volumes are tantalizing titles that hint at all the history lost from the building's destruction.
One of the stories about what caused the loss of the Library concerns Julius Caesar. Edward Parsons has analyzed this theory in his book The Alexandrian Library. His summary is:
The majority of ancient historians, even those who have tried to discredit Caesar with everything they could find, give no account of the alleged massive disaster. This is hardly surprising when we note that the library was not mentioned by any historians while it still existed either. We have only one contemporary reference to it and that is in the Jewish apographical work, the Letter of Aristeas. It is also inconcievable that Seneca, Plutarch, Aulus Gellius and Ammianus would be writing about the destruction of the library if it still existed! We cannot be sure it was destroyed by Caesar but we can be sure it no longer existed by about 100AD.
It is also notable that Plutarch, who claimed the Great Library was destroyed (150 years after the alleged incident), in Life of Antony also describes the later transfer of the second largest library to Alexandria by Mark Antony as a gift to Cleopatra ("that he had given her the library of Pergamus, containing two hundred thousand distinct volumes"). We should note, however, that Plutarch himself states this story was propaganda by Antony's enemies and that the excavated library at Pergamum has room for only about 30,000 scrolls anyway.
The destruction of the library is attributed by some historians to a period of civil war in the late 3rd century AD -- but we know that the Museum, which was adjacent to the library, survived until the 4th century. Other theories involve the hand of Theophilus[?], a Christian bishop, or the Caliph Omar, an early Muslim. "The Venerable Bede" argues that both of these accounts have many issues regarding their reliability. The account which indicts Theophilus, he claims, is simply incorrect on the time scale and location. The first writer to mention Christians destroying the Library was Edward Gibbon in the 18th century - no ancient sources say so at all. For Omar, he concludes that the theory seems to have begun in the Middle Ages as a Christian attack on the Muslims, and includes many indications of fabrication, such as the claim that the contents of the Library took six months to burn in Alexandria's public baths.
It is generally known that Theophilus did in fact destroy some pagan temples that existed in Alexandria in 391 AD, most famously the Serapeum, but it is uncertain whether the Serapeum still contained books at the time or whether those had been lost earlier. Ammianus, a pagan historian, says it did not. Socrates Scholasticus gives the following account of the destruction of the temples:
The following scroll from the early 5th century illustrates the destruction of the Serapeum by Theophilus (source: Christopher Haas: Alexandria in late antiquity, Baltimore 1997):
To commemorate the ancient library, the government of Egypt has built a major library and museum complex at Alexandria, called the Bibliotheca Alexandrina. Its website is available at http://www.bibalex.gov.eg (http://www.bibalex.gov.eg).