The great library of Alexandria no longer exists, but it’s not known for sure when the library was destroyed. There’s actually considerable debate among historians about who destroyed the library and when. One culprit who has traditionally been accused of destroying the library at Alexandria is Julius Caesar. It’s true that Julius Caesar led an invasion of Alexandria in 48-47 B.C and that, at that time, his forces set the fleet of ships sitting in the Alexandria harbor on fire. Some historians believe that this fire in the harbor that was set by Caesar’s forces, spread into the city of Alexandria and burned the library down, but this belief is no longer widely held today.
The main reason that the theory that Julius Caesar destroyed the library at Alexandria isn’t widely believed is that there are numerous references to the library in works written long after Caesar’s death.
The conclusion that seems to be most accepted today is that the library at Alexandria existed, at least in part, until the late fourth century, centuries after the death of Julius Caesar, so it could not have been completely destroyed by Caesar.
At that time, at the end of the fourth century, there was a large movement to destroy pagan temples and libraries. It seems likely that whatever remained of the library of Alexandria was destroyed at this time.