I read this technically astounding book that exposed the truth about the pyramids: all pyramids around the world are located at points where the fundamental harmonic vibrations of the earth (wavelength = 1 earth diameter or something like that) form natural standing waves. If you stand on top of giza and speak in a natural voice, someone standing on top of chichen itza can hear you beause the sound waves will travel sthere with no distortion due to the standing wave effect. They are big walkie talkies. Plus, they have the added effect of being able to recharge your batteries.
It's all true!