The Venetians shelled the Parthenon and set off explosions in the ammo the Turks had stored in or near it, and the explosion did much of the damage.
The rest of the damage was done over a period of several generations by the British Museum, because the marbles looked dirty.
https://en.wikipedia.org/wiki/Elgin_Marbles
True, that. But the Venetians wouldn’t have had to shell it if the Turks weren’t using the top of the Parthenon hill as a fortress. And if they hadn’t stored ammunition in it.