The Library of Alexandria was inspired by the Greek culture and established by Ptolemy, following the design of Aristotle's Lyceum. It was housed in the Serapeum, part of a larger museum and palace complex. How it was destroyed is uncertain, various candidates being Julius Caesar, Patriarch Theophilus and Caliph Omar. However, it is likely that accidental fire damage was the culprit.
Foundation and early years
The Library of Ancient Alexandria was established between 367 and 283 BC by Ptolemy Soter, the Greek pharaoh of Egypt. Its aim was to keep a copy of every book in the world, and messengers were sent around the Mediterranean, seeking books. It was housed in the Serapeum, a building designed to resemble Aristotle's Lyceum, his school at Athens, with courtyards where scholars could walk and discuss. This was part of a museum complex, the Bruchion.
By the time of Caesar's arrival in Egypt, the royal library included 500,000 books and the public library 42,000. However, it was during the fighting that beset Egypt during this time that the first damage to the library is mentioned. Ancient writers mention that fighting caused the fire to spread to the library, Seneca quotes from Livy, saying that a great number of books were destroyed.
However, the scholarly emperor Claudius (41-54 AD) gave a donation of books, as did the Emperor Hadrian at a later date. That implies that library activity was still going on in the second century. It is likely that damage in Caesar's time occurred, but was not total.
What is certain is that by the twelfth century the library was gone, as John Tzetzes, a Christian scholar affirms in his work. However, scholars argue who was to be blamed. Caesar was accused early, but any damage in his time was accidental, the side effect of war.
Gibbon accuses Patriarch Theophilus. However, Gibbon's objectivity as a historian is seriously criticised by modern scholars, as he is recognised to have an anti-Christian bias. There is no evidence to link Theophilus to the destruction. Gibbon's argument seems to imply that as it was not Omar who destroyed it, it must be Theophilus. That's a weak argument.
Accused by some medieval writers is Caliph Omar. This claim is mere propaganda. There is no evidence that Omar burned the library. As he was quite civilised and merciful in his treatment of conquered cities, we can dismiss it as a fiction from Islam's enemies.
Most likely, the library was not intentionally destroyed, but was caught up in the fire that burned the crowded city: Either accidentally or during civil unrest. The Bibliotheca Alexandrina is a modern library established near the site.