Maina

As for the occurrence of pi in the Pyramid's measurements, the Egyptians may have arrived at this transcendental number without realizing it. Most scholars believe that the Egyptians didn't know the ratio of the circumference to the diameter of a circle to a greater accuracy than three for more than a thousand years after Khufu. Therefore, the occurrence of pi may be due to the fact that the Egyptians may have measured long horizontal distances …

…in the field of Egyptology. But Mark Lehener does seem to be making progress through empirical scientific method and a survey that looks at the whole picture. Of course there is no way to disprove the theory that space aliens aided in the construction of the pyramids. But there isn't any concrete evidence to make it likely either. But the how is not my concern here. The why of the pyramids is the great issue.