Constructed as tombs for the ancient pharaohs, over 100 pyramids remain in Egypt. Built during a span of well over 1,000 years, they stand as cultural and engineering marvels of staggering proportions. But many things about these monuments, including the exact methods used to construct them, remain tantalizingly obscure. Travel back in time as we investigate their evolution–from the earlier mastaba to the Step Pyramid, Bent Pyramid, and of course, the magnificent necropolis at Giza.