While many people assume that those living in earlier times (such as the ancient Egyptians) were not resourceful enough to possibly have created impressive engineering feats without extraterrestial aid, this is not true. Actually, the methods by which the pyramids could have been constructed are well documented, and have appeared in many places including National Geographic magazine and Mark Lehner’s book The Complete Pyramids. The only real mystery surrounding the pyramids is why anyone would still think aliens were involved.

Further reading:

Mark Lehner. The Complete Pyramids.