The apparently very popular History Channel documentary, Ancient Aliens, correctly posits that for the Great Pyramid of Giza to have been aligned perfectly to true north (as it is), the ancient designers of it must have measured time in order to determine longitudes, and thereby, know where the longitude lines intersect at the poles, to determine true north (and south), but since such accurate timekeeping is thought by most to have been impossible back in the 2200 B.C. timeframe (with such accuracy achieved only about two centuries ago), they say that extraterrestrials, the ancient aliens, must have been responsible, with advanced technology.
However now then after you do understand the simple explanation of how mere humans measured the earth with a simple device (refer to article #2 at http://IceAgeCivilizations.com) by the slow wobble rate of the earth’s axis, and thereby mapped it too, the same methodology used to survey the Great Pyramid, you’ll see that Ancient Aliens were certainly not needed, much to the chagrin of New Agers and mainstream scientists who refuse to believe that the ancients circa 2000 B.C. were measuring, mapping, and navigating the globe, actually during the Ice Age, in full corroboration of the Genesis account, which is why mainstream scientists don’t like talking about the methodology in the link, so put it in front of them please. See http://genesisveracityf0undation.com.