For 45 centuries, the Great Sphinx has cast its enigmatic gaze over Egypt's Giza plateau. The biggest and oldest statue in a land of colossal ancient monuments, its scale is staggering; the mighty head towers as tall as the White House while its body is nearly the length of a football field. How was it built, and who or what does represent? NOVA's expert team of archeologists carries out eye-opening experiments that reveal the techniques and incredible labor that was invested in the carving of this gigantic sculpture.