The pyramids were probably massive public works projects, with off-season farmers making up the workforce, paid in beer. Not slave labor.

Actually, a metal machinist from the Midwest named Christopher Dunn has a fascinating theory that the great pyramids may have actually been 'power plants' of a sort.

Giant harmonic resonators that siphon energy off of the earths expansion and contraction caused by orbit of the moon.

http://www.amazon.com/Giza-Power-Plant-Technologies-Ancient/...

His writing is a bit dense, and maybe not as smooth as it could be...but his exploration of the possibility is quite impressive.

As you're by all appearances unaware of the concept, a bit of light reading...

https://en.wikipedia.org/wiki/Pseudoscience

and https://en.wikipedia.org/wiki/Scientific_theory (with an emphasis on the "well substantiated" bit)