The Library of Alexandria was not destroyed in a single fire, but declined over several centuries.
Why it is true
Ancient accounts mention fires, funding cuts and conflicts, but there is no proof of a single event that erased it. The decline was gradual and involved the loss of support and the dispersal of scholars.
Source: Smithsonian
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.