Pyramids have been built by civilizations in many parts of the world. For thousands of years, the largest structures on Earth were pyramids—first the Red Pyramid in the Dashur Necropolis and then the Great Pyramid of Khufu, both of Egypt, the latter the only one of the Seven Wonders of the Ancient World still remaining. Khufu's Pyramid is built mainly of limestone (with large red granite blocks used in some interior chambers), and is considered an architectural masterpiece. It contains around 1,300,000 blocks ranging in weight from 2.5 tonnes (5,500 lb) to 15 tonnes (33,000 lb) and is built on a square base with sides measuring about 230 m (755 ft), covering 13 acres. Its four sides face the four cardinal points precisely and it has an angle of 52 degrees. The original height of the Pyramid was 146.5 m (488 ft), but today it is only 137 m (455 ft) high, the 9 m (33 ft) that is missing is due to the theft of the fine quality white Tura limestone covering, or casing stones, for construction in Cairo. It is still the tallest pyramid. The largest pyramid by volume is the Great Pyramid of Cholula, in the Mexican state of Puebla. <wikipedia>