The Ancient Egyptians accomplished many construction feats including building the massive pyramids out of limestone blocks weighing around 2.5 tons each. The pyramids, such as the Great Pyramid of Giza, demonstrate the Egyptians' knowledge of mathematics and geometry. Other accomplishments were developing the Sphinx, which guards the pyramids, and establishing elaborate rituals of mummification to preserve bodies for the afterlife. Their system of writing also evolved from early pictographs to the more efficient hieroglyphic script.