Along with the many theories about the origin of the Egyptian pyramids, there are those that believe the work of the Pyramids took place under the work of aliens. These theories are based on the following evidence:
Both diagonals of a pyramid in some cases can continue to extend beyond the northeast and northwest, meaning the fully protect the Nile Delta. This is not possible to achieve with human effort, as space is extremely large and diagonals have to be located with precise accuracy. This could only be achieved by aircraft which are flying high enough above the ground to see where the delta of the Nile is and how to build a pyramid so that its diagonals lay on those two lines.
Again, it appears that the Great Pyramid lines up exactly with the magnetic North Pole with only a small difference. It is believed that it is not possible for Egyptians to had built the pyramid because they did not have a compass. The compass was invented several thousand years later. Maybe alien civilizations with their knowledge and new technologies could establish the actual time of the magnetic North and South Pole?
The location of the Sphinx, Great Pyramid of Giza and neighboring Pyramid in the summer evenings show the sun located exactly between the two pyramids. Then it would had been necessary for the to know precisely the day of the summer solstice, and be able to determine that only if they know the exact length of the year, namely 365 days, a fact which was discovered much later.
The location of the three Pyramids of Giza is exactly consistent with the position of three stars in the constellation Orion, as position and size. While it is possible, it would create difficulties for the Egyptians in terms of measuring large distances.
It seems more plausible that the possibility of aliens came to the earth in 10, 500 BC and built these Pyramids and Sphinx. They had made the head of a lion, which corresponds to both the constellation Orion and the constellation Leo. Thousands of years later, the Egyptian Pharaoh Ramesses decided that he wanted to have his statue in the lands with the lion head and ordered one to be put the same along the lines of the lions head. However no Egyptian had much experience in masonry and built the head too small.
Another interesting fact is that if the perimeter of a pyramid is divided by twice the height, it is given a figure equal to the number pi, estimated 14, 159 until the fifteenth figure. The chances of this happening are generally very small. It is unlikely that the ancient Egyptians can not know what is the number pi, because it was not calculated accurately to the fourth digit to the VI century, when even the pyramids are calculated until the fifteenth.
Interesting is the fact that although the parties on the basis of the pyramid is approximately 757 feet long, it was almost a perfect square. Every corner of its base is exactly 90 degrees. Possibility of this being achieved by human effort is extremely small.