The Library of Alexandria wasn't destroyed in a single fire

The popular image of Julius Caesar accidentally burning the Library of Alexandria in 48 BC is misleading. The library declined over several centuries through a combination of funding cuts, political upheaval, and partial fires including those under Caesar, Aurelian (270s AD), and Theophilus (391 AD). It was never a single catastrophic loss but a slow erosion of support. Historians now believe most of the collection had already been dispersed or lost long before any dramatic fire — the myth of a singular burning is more compelling than the mundane reality of institutional neglect.

Source: MacLeod, The Library of Alexandria (2004)