Egypt's Great Pyramid weighs close to six million tons and contains roughly 2.3 million stone blocks, raised by a civilization that had not yet invented the wheel. This Naked Science episode sets out to answer four questions about it: how it was built, who built it, why, and what might still be hidden inside. British engineer Denys Stocks, who has spent twenty years reconstructing ancient quarrying and stone-fitting methods, demonstrates the physical techniques on camera, while construction manager Craig Smith works out what the project would cost in modern money. Archaeologist Mark Lehner takes viewers through the excavated town where the builders actually lived, and Zahi Hawass tours their tombs, evidence used to challenge the old story that slaves did the labor. Salima Ikram and Jim Allen read the hieroglyphic spells inside the chambers for clues to the pyramids' purpose, and Robert Bauval argues for a deliberate alignment with the stars. The film closes with robots exploring the Great Pyramid's internal shafts, still hunting for chambers no one has entered.