Hello, r/AskHistorians community, this is my first time posting on this sub.

I've been researching the Library of Alexandria recently, and I have come to notice certain misconceptions that circulate around the whole controversy of when and why the Library was burnt down. The popular conception which has been floating around in recent years is that the Library was burnt by a Christian mob sometime in the 4th century, a view which has been popularized by the movie Agora. Yet the Library seems to have an extensive history of being burnt and rebuilt, with the first instance, during the reign of Julius Caesar, being documented by Cassius Dio, and some speculation that a functional library still existed in the seventh century before the Rashidun invasions. It would seem that by then, and even well before the Christianization of the Empire, the vast majority of the collection had been evacuated. So what do you think is the likeliest date and cause of the 'burning' of the Library?