The great pyramids at Giza -- awe inspiring icons of Ancient Egypt. But these monuments are not unique. Thousands of pyramids have been built all across the globe. Dr. Kara Cooney travels from the very first pyramids in Egypt to the temples of Mexico, and even to round pyramids in Sri Lanka, demonstrating that the history of these buildings hides a long and twisted evolution of architecture and form. Ancient pyramid builders everywhere attempted to master an ideal sacred shape, but what did the pyramid really mean to the ancient people? And why did they work so hard to perfect it?