The Great Pyramid of Giza is the oldest and largest pyramid at the site. This pyramid was probably built by the cousin of Khufu, named Hemiunu. The Great Pyramid of Khufu covers 13 acres at its base and is approximately 137 meters (450 feet) in height. It was originally cased with polished limestone, creating a smooth exterior. Over the years, the smooth limestone was looted and used in other parts of the world. The pyramid of Khafre is slightly smaller than Khufu.