
Alexandria was founded in Egypt by Alexander the Great. His successor as Pharaoh, Ptolomy II Soter, founded the Museum or Royal Library of Alexandria in 283 BC. The Museum was a shrine of the Muses modeled after the Lyceum of Aristotle in Athens. The Museum was a place of study which included lecture areas, gardens, a zoo, and shrines for each of the nine muses as well as the Library itself. It has been estimated that at one time the Library of Alexandria held over half a million documents from Assyria, Greece, Persia, Egypt, India and many other nations. Over 100 scholars lived at the Museum full time to perform research, write, lecture or translate and copy documents. The library was so large it actually had another branch or "daughter" library at the Temple of Serapis.
In Edward Gibbon's "The Decline and Fall of the Roman Empire" Theophilus was Patriarch of Alexandria from 385 to 412 AD. During his reign the Temple of Serapis was converted into a Christian Church (probably around 391 AD) and it is likely that many documents were destroyed then. The Temple of Serapis was estimated to hold about ten percent of the overall Library of Alexandria's holdings. After his death, his nephew Cyril became Patriarch. Shortly after that, riots broke out when Hierax, a Christian monk, was publicly killed by order of Orestes the city Prefect. Orestes was said to be under the influence of Hypatia, a female philosopher and daughter of the "last member of the Library of Alexandria". Although it should be noted that some count Hypatia herself as the last Head Librarian.
Alexandria had long been known for it's violent and volatile politics. Christians, Jews and Pagans all lived together in the city...there was mass havoc as Christians retaliated against both the Jews and the Pagans - one of which was Hypatia. The story varies slightly depending upon who tells it but she was taken by the Christians, dragged through the streets and murdered. Some regard the death of Hypatia as the final destruction of the Library. Others blame Theophilus for destroying the last of the scrolls when he razed the Temple of Serapis prior to making it a Christian church. (Source eHistory Archive)

In the late fourth and early fifth centuries of our era, Hypatia of Alexandria was the world's greatest living mathematician and astronomer. A strikingly beautiful woman and a devoted celibate, she lived in a city as turbulent and troubled as Baghdad or Beirut is today. She achieved fame not only in her special field, but also as a philosopher, religious thinker, and teacher who attracted a large popular following. Her life ended tragically in violence at the hands of a rampaging mob of Christian fanatics, who killed her for her "pagan" beliefs, some say at the instigation of St. Cyril of Alexandria.

"It was political developments that brought all this to an end. In 378 the Roman legions had suffered a devastating defeat by Gothic forces at Adrianople in the Balkans. The emperor Valens died leading his troops. In the ensuing panic the remaining emperor, Gratian, appointed a tough Spanish soldier, Theodosius, as emperor over the Greek-speaking eastern half of the empire. Theodosius was desperate to restore order before the empire fragmented under the pressure of the “barbarians”. One way of doing this, he believed, was to strengthen the empire under a single religious formula. A supporter of the Nicene formula himself, Theodosius dramatically broke with the policy of toleration by announcing that henceforth only Nicene bishops could have churches within cities, and that other Christians, now dubbed “demented and insane heretics”, would have to give up their churches and be subject both to imperial and divine vengeance. When he entered his capital, Constantinople, for the first time in 380, Theodosius enforced his policy and the “subordinationist” bishop of the city was immediately dismissed."
Charles Freeman

"It was a mark of Constantine's political genius and flexibility that he realized it was better to utilize a religion(Christianity) that already had a well-established structure of authority as a prop to the imperial regime rather than exclude it as a hindrance."
"The argument of this book is that the Greek intellectual tradition did not simply lose vigor and disappear. (Its survival and continued progress in the Arab world is testimony to that). Rather in the fourth and fifth centuries AD, it was destroyed by the political and religious forces which made up the highly authoritarian government of the late Roman empire. "
Charles Freeman