National Geographic: Unlocking the Great Pyramid

It marks one of the greatest engineering enigmas in world history: how exactly did the builders of the Great Pyramid of Giza manage to lift limestone blocks of 2.5 tons each a distance of nearly 500 feet off the ground - without the advantage of modern technology? That riddle has inspired generations of historians and researchers to comb every interior and exterior inch of the pyramid, measuring distances and amassing data to arrive at a conclusion. But only recently have more definite answers come to light - answers that originate inside of the Pyramid. The documentary program National Geographic - Unlocking the Great Pyramid discusses this arresting theory.