How were the blocks raised to the top of the 489 ft Great Pyramid? An architect develops a theory about a snaking internal ramp that's been hidden inside the pyramid for 4500 years.---------------------------------Unlocking the Great PyramidWhen ancient architects completed construction on the Great Pyramid at Giza, they left behind the greatest riddle of the engineering world—how did builders lift limestone blocks weighing an average of two and a half tons 480 feet up onto the top of the Pyramid? For centuries, adventurers and Egyptologists have crawled through every passageway and chamber of the Pyramid, measuring and collecting data in an attempt to determine how it was built. For the first time, a revolutionary theory argues that the answer may be inside the Pyramid. National Geographic follows renowned experts Architect Jean-Pierre Houdin and Egyptologist Bob Brier as there set out to solve the mystery of how the Great Pyramid was built. On an expedition to Giza, the pair uses Houdin's detailed blueprints of the structure and 3-D software to unlock the secret. Is Houdin's theory true that a ramp used during construction still exists inside the pyramid? The answer to this and other questions is revealed in this enthralling expedition to the Great Pyramid.