“In those flames (The Burning of the Library of Alexandria), the history of the world before the great cataclysms was lost forever; the science of the Magi and the astronomical secrets of the Chaldeans vanished, leaving us to wander in the dark.” ― Pike, A. (1871). Morals and Dogma of the Ancient and Accepted Scottish Rite of Freemasonry.
The library was part of a larger research institution called the Mouseion, which was dedicated to the Muses, the nine goddesses of the arts.
It was first damaged by fire during Julius Caesar's siege of Alexandria in 48/47 BCE. The Serapeum, a daughter library, was destroyed in 391 CE by Christian forces under Bishop Theophilus. The final destruction is traditionally attributed to the Arab conquest of Alexandria in 641 CE, when Caliph Umar is said to have ordered the library's books burned to heat the city's baths, though this account is debated. The library had already declined significantly by the 3rd century CE due to lack of funding and political instability.
Size: Estimates vary; somewhere between 40,000 and 400,000 scrolls, perhaps equivalent to roughly 100,000 books.