All of this is available at your local university or public library. Go look it up. That any of this is entirely mysterious is a myth propagated by cultists and psuedosientists.
Davin L.

It is true that there is a lot of information in the libraries of today, but as I understand it, those writings are mostly conjecture derived from bits of physical evidence from construction methods that have been "supposed" to exist during the time period of their construction. There still seems to be some discrepancy as to "when" the pyramids were constructed. Some authors state that they were build about 4,000 years ago but some say that there is evidence that they were constructed earlier, or about 10,000 years ago.

It is said that long ago there used to be a great library in Alexandria, that contained among its 700,000 volumes of writings, information that dated back to the time when the pyramids were build. What a shame that such information does not exist anymore.

I know that it is hard to imagine that someone four thousand years ago could have been smarter in some ways than you are today but such might have been the case.

I have read somewhere that there are old Sanskrit writings about how the stones of the pyramids were moved to the construction site, they do not tell of long ropes and thousands of slaves, but you would not believe such stories because it would involve the understanding of such phenomenon as transverse and longitudinal vibrations in synchronized resonance within the material being moved.

Johannes

Human Nature
The nature of peoples is first crude, then severe, then benign, then delicate, finally dissolute.