Constructed between 2589 and 2504 B.C., the Egyptian pyramids of Khufu, Khafre and Menkaure, built in that order, are a testament to ancient planning and engineering.
How these pyramids were built is a source of speculation and debate. Many researchers believe that a ramp system of some form was used to move the blocks into place during construction. When the pyramids were completed they were encased in white limestone, most of which is lost today.