Which time?

The most commonly known was in 48BC when Caeser was besieged in the city he set fire to his won ships, the fire then spreading to the docks and then the city. At least according to Plutarch's account. Many of those works though were reportedly replaced. Mark Antony according to Strabo plundered the library at Pergamon and presented the books as a gift to Cleopatra. This act was used against him in Rome to show how he was loyal only to her and Egypt now.

But there were also fires that destroyed sections of the city and parts of the library that were rebuilt in the 270's when the country revolted against the Emperor Aurelian, and in 391 when paganism was outlawed under Theodosius and the pagan temples were destroyed.

At the end of the day it seems unlikely that anything was destroyed there which was irreplaceable, there were multiple famous and important centers of learning around the Mediterranean world, and copies of works could be very widely distributed.

hi! you'll find more responses in these threads

• Library of Alexandria

• Why did Julius Caesar burn down the Great Library of Alexandria?

• Were there causes for the destruction of the Library of Alexandria that weren't exactly religious?

• How was the library in Alexandria destroyed?

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