There is a consensus about the theory that the megalithic sites around the world, including the Egyptian pyramids, were built by ancient civilizations using advanced technology we don't understand, and were exterminated by a cataclysmic event. And that these structures, such as that at the Giza Plateau, were energy generators.
Two questions that come to mind immediately:
1) If indeed such ancient civilizations existed, why haven't any of their traces found? Surely there would have been bones and remains found somewhere from such a population - and if we found dinosaur bones that existed 65 million years surely we can find remains of humans who roamed the earth 12,000 years ago?
2) There is a popular suggestions that these monuments, such as the Egyptian pyramids, were not tombs but energy generators. What kind of energy are they referring to? Electric? Radioactive? Sound?