Stargate anyone?
The third major pyramid (small by Giza standards, but still large) was going to be torn down by a caliph during the Middle Ages, and the scar from that attempt still shows, but after months of work, he went out to take a look, saw how little damage had been done so far, and gave up. His goal was to rip down all three of ‘em.
The Abu Roash pyramid of Khufu’s son and successor, Djedjedfre, a few miles north of Giza, was constructed to some point during his shortened reign, but during recent centuries it’s known to have become a quarry of sorts for Muzzie projects in Cairo.