Kufu's pyramid was actively used. It's the only likely reason for the design of it's portcullis, which doesn't defend as well against entry as previous designs, and is equipped for repeated opening. Plenty of information on the topic here:

https://www.youtube.com/watch?v=ItAQSrlG9WQ

https://www.youtube.com/watch?v=r5Qe7xDf_ks