What happened to the Royal Library of Alexandria? We can be certain it was there once, founded by Ptolomy II Soter, and we can be equally certain it is not there now. It formed part of the Museum which was located in the Bruchion or palace quarter of the city of Alexandria.
The suspects respectively are a Roman, a Christian and a Moslem - Julius Caesar, Patriarch Theophilus of Alexandria and Caliph Omar of Damascus. It is clear that the Royal Library could not have been burnt down or otherwise destroyed by all three of these characters and so we find we have too many sources for the event of the destruction rather than a paucity.