Great Pyramid of Giza, Egypt

Built for Pharaoh Khufu around 2560 BC, the Great Pyramid of Giza stood as the tallest human-made structure in the world for 3,800 years at 146.5 metres. Constructed with approximately 2.3 million stone blocks weighing an average of 2.5 to 15 tonnes each, it was built with such precision that the four base sides differ in length by less than 5 centimetres. It is the only one of the original Seven Wonders of the Ancient World still intact.