The peak of Mt. Everest is the highest point on earth, at 29,034 feet above sea level. Mt. Everest is also rising at an approximate rate of one centimeter per year due to the movement of the continental plates that formed the Himalayas in the first place. Based on this reckoning, Mt. Everest would have been approximately 150 feet lower 4,500 years ago, when the Great Pyramid is believed to have been constructed. At 28,884 feet above sea level, Mt. Everest would have been an even 1,440 times shorter than the diameter of the earth. Mt. Everest was also exactly 60 times taller than the Great Pyramid, 4,500 years ago:

481.4 feet x 60 = 28,884 feet.

This is an interesting synchronicity, given the ancient base 60 systems of arithmetic that have left us with the twin legacies of a base 60 system of time:

60 seconds = one minute / 60 minutes = one hour

and a base 60 system of distance:

60 seconds = one minute / 60 minutes = one degree.