TODAY IS THE ANNIVERSARY OF THE FOUNDING OF THE LIBRARY OF ALEXANDRIA, at least according to the Egypt State Information Service. They don�t give an ancient source and I have no idea if we actually know even the year it was founded, let alone the day, but this is a good excuse to round up some things on the Library. Here�s a great website on the Library of Alexandria for a course on Greek science at Tufts University. There is a new library in Alexandria meant to emulate the ancient one, and it is discussed in this National Geographic article. There is also an online Digital Library of Alexandria under construction. According to the legend in the Letter of Aristeas, King Ptolemy II (285-247 B.C.E.) ordered the librarian, Demetrius of Phalerum, to commission a translation of the Pentateuch in Greek. This was done by seventy-two translators from Palestine in seventy-two days. The story was written long after the fact, but most specials seem at least to accept the third-century date for the translation of the Pentateuch.
The main library was destroyed, apparently accidentally, by Julius Caesar in a battle with Pompey. The associated library of the Temple of Serapis may have survived much longer and there are various legends about its destruction. Evaluations of the evidence for the destruction of the Library of Alexandria can be found here, here, and here.