The Great Pyramid of Giza is a huge pyramid built by the Ancient Egyptians. It stand 18.4 km from Cairo, Egypt. It is the oldest of the Seven Wonders of the Ancient World, and the only one to remain mostly intact. When it was built it was 146.5 metres (481 feet) tall. It was the tallest building in the world for over 3,800 years. Erosion and other causes have shrunk it to 138.8 metres. The pyramid was built for Khufu, an Egyptian pharaoh. It was perhaps built by Khufu's vizier, Hemiunu. It is believed that it took about 20 years to build, and was completed around 2570 BC.