The Great Pyramid was built 4,500 years ago, yet experts estimate that it would cost close to $5 billion to replicate today. By comparison, it cost nearly $4 billion to build World Trade One, which is the most expensive building in the world.
The Great Pyramid stands 481 feet high and is 756 feet long in each direction. It was built using 2.3 million stones, each weighing 3 tons - for a total massive weight of 6.5 million tons. It took over 20 years and 4,000 workers to complete the structure.
French architect Jean Pierre-Houdin, working at the Laval University in Quebec, created a computer model of The Great Pyramid and proposed a new theory on how it was built. For the bottom two-thirds, workers used sleds and ropes to pull stones up the walls on the outside of the pyramid. This is similar to established theories. For the top third, however, he believes that a gradual spiral ramp was built on the inside, and workers pulled stones up to the top using the ramp.
If humans were to recreate The Great Pyramid today, they would likely need to use spiral ramps just like the Egyptians, argues Pierre-Houdin. Based on his studies of the Hoover Dam, he estimates that it would take about 5 years and 1,500-2,000 modern day construction workers to complete a modern duplicate.
His approximation includes using modern equipment like cranes and helicopters, too, which is a testament to the engineering ability of the Egyptians and the longevity of The Great Pyramid.