The Great Pyramid of Giza is the oldest and largest of the three pyramids in the Giza pyramid complex and the only one of the Seven Wonders of the Ancient World to remain largely intact. Built as a tomb for the Fourth Dynasty pharaoh Khufu around 2560 BC, it was the tallest man-made structure in the world for over 3,800 years. It is estimated to consist of 2.3 million stone blocks, some weighing up to 80 tons. The precision of its alignment to true north is remarkable, with an error of only three-sixtieths of a degree. Inside, it contains the King's Chamber, the Queen's Chamber, and the Grand Gallery. Originally, the pyramid was covered in smooth white 'casing stones' made of highly polished limestone that would have reflected the sun's light, making it shine like a jewel in the desert.