Beneath the pyramids is a mystery..hidden chambers leading to underground...city ..preserved ...hidden... concealed ..till right humans and right time will it all be revealed ..at the moment some knowledge is known but not all.

There is a “lost” underground city beneath the Giza pyramids that have been well documented in the past, despite the fact that entry to it is currently prohibited by the authorities.

check this out @

https://knowledge-time.com/a-huge-ancient-city-lies-beneath-the-great-pyramids-guarded-by-robots-of-an-advanced-past-civilization-many-ancient-writers-and-historians-claim-4361/? 

Quote from article : 

A text by the Arab writer Altelemsani, which is preserved in the British Museum, contains more proof of the “subterranean metropolis” beneath the Giza pyramid. The existence of a big square underground room located underground, between the Great Pyramid and the Nile River, is mentioned by Altelemsani. Something massive, according to Altelemsani, was blocking the Nile River’s entrance.

Interestingly, a writer named Masoudi stated in the ninth century that some advanced mechanical sculptures guarded the underground corridors beneath the Great Pyramid of Giza. Its description, written over a thousand years ago, is comparable to today’s digital robots. According to Masoudi, these robots were programmed to kill everyone except those who, based on their actions, deserved to be welcomed inside.