Since its construction 4,500 years ago for Pharaoh Khufu, the Great Pyramid of Giza has remained an engineering mystery. According to Egyptologist Brier (The Murder of Tutankhamen) and architect Houdin, the monument was designed by Khufu's brother Hemienu, an architectural genius, and built in two decades by 25,000 paid Egyptian construction workers. Having studied the structure minutely and using computer graphics to visualize every aspect of the pyramid and its construction, Houdin offers a radical proposal of how the huge limestone and granite blocks were raised: the pyramid was built from the inside out around a mile-long ramp corkscrewed up to the top, which remains in the pyramid's walls.