diameter of a circle and its circumference. Consider this: The height of the Pyramid's apex is 5,812.98 inches, and each side is 9,131 inches from corner to corner (in a straight line). If the circumference of the Pyramid is divided by twice its height (the diameter of a circle is twice the radius), the result is 3.14159, which just happens to be pi. Incredibly, this calculation is accurate to six digits. So the Pyramid is a square circle, and thus pi was designed into it 4,600 years ago. Pi is demonstrated many times throughout the Pyramid.  Other numbers are also repeated throughout. Each of the Pyramids four walls, when measured as a straight line, are 9,131 inches, for a total of 36,524 inches. At first glance, this number may not seem significant, but move the decimal point over and you get 365.24. Modern science has shown us that the exact length of the solar year is 365.24 days.  All of the evidence in the Great Pyramid shows that 4,600 years ago somebody knew a great deal about the Earth. But it gets better, much better:
     The average height of land above sea level (Miami being low and the Himalayas being high), as can be measured only by modern-day satellites and computers, happens to be 5,449 inches. That is the exact height of the Pyramid. All four sides of the Pyramid are very slightly and evenly bowed in, or concave. This effect, which cannot be detected by looking at the Pyramid from the ground, was discovered around    1940 by a pilot taking aerial photos to check certain measurements. As measured by today's laser instruments, all of these perfectly cut and intentionally bowed stone blocks duplicate exactly the curvature of the earth. The radius of this bow is equal to the radius of the Earth. This radius of curvature is what Newton had long been seeking.

The Great Pyramid is located on the far right.

Clearly, whoever built the Pyramid had access to information beyond that which earthlings possessed at the time, at least earthlings, as we know them. Now, one can argue that we were visited by scientifically advanced beings from outer space that taught us their technology. That is possible from the evidence presented, perhaps even likely. If so, these advanced beings had the paramount goal of leaving behind a message that would endure for eons.
Suppose these beings decided to leave a message. The message would have to be universal yet simple. It would have to survive the centuries and be understandable by all the Earth's inhabitants despite language and cultural differences. The message would have to be understood by many languages that would not come into existence for centuries after the message was written. 
So far the message indicates that whoever built the Pyramid knew the Earth well: the length of the year, the radius of curvature, the standard measurement techniques, the average height of the
Continents, and the center of the landmass. They were able to construct something that we still cannot construct today, and they were able to tie all these things together in this single structure.
Were they extraterrestrial, or perhaps even supernatural? The answer is not yet clear. However, thus far we have examined only the outside of the Pyramid.