There is no shortage of theories about how the pyramids were built, in particular the gargantuan Great Pyramid Of Giza. It is of such size, magnitude, and architectural awesomeness that few believe it could have been built by ancient humans without some help.
On an interview on Coast to Coast AM, author Patrick Heron has his own theory, that the nephilim of the Bible are behind it. Here’s the theory.
https://www.youtube.com/watch?v=onWHkJO0m3M