The pyramids of ancient Egypt are such an incredible achievement that it's easy for us to believe they weren't the work of humans at all--just see the groups of people who believe that divine intervention or aliens were required for their construction. But as this video shows, Egyptians used brilliant if rudimentary technology to get the job done. Though they didn't have wheels, they used tricks like wetting the sand to reduce friction for the sleds that carried their tons of stone. The pyramids at Giza were also built directly next to a quarry, which made transporting all that stone easier. Figuring out the cardinal directions and creating 90 degree angles would have been tricky back then, but by following the stars and making a basic level, it was totally doable. Researchers now have concluded that the Great Pyramid probably took fewer than 2,000 people to build over 23 years. What have you done lately?