Constructing the Pyramids of Giza would prove a difficult undertaking for modern engineers with advanced technology, so the question of how ancient Egyptians built the pyramids has long perplexed historians and archaeologists. Specifically, the puzzle of how ancient Egyptians lifted and moved the pyramid blocks - some of which weighed dozens of tons - from quarries to the build sites across miles of the desert has led to endless theorizing.
While individuals with questionable scientific credentials have attributed the construction methods to supernatural forces, more serious Egyptologists have devised numerous theories that provide plenty of explanations - and a moderate amount of evidence - for how the pyramids were built. It appears the answer is not ancient aliens, but instead the inherent ingenuity of an ancient culture determined to leave their permanent mark on the world.
The Egyptians erected the Pyramids of Giza more than 4,000 years ago, but the intervening millennia are not the only reason their construction remains so mysterious. In addition to leaving most of their records in difficult-to-decipher hieroglyphs, it's also quite likely ancient Egyptians specifically chose not to document the methods behind the pyramids.
Egyptologist Kara Cooney explains why they might have kept their building techniques to themselves:
Any authoritarian regime is going to hide their secrets as long and as best as they can. The pyramids are there as mountains of stone proving the otherworldly nature of their god-kings. You stand in front of those pyramids, and you feel it's impossible to build such a thing... The propaganda is still working.
The quarries used to mine granite for the pyramids brimmed with natural "obelisks" of rock that should have been impossible to remove from the ground with ancient technology. Instead, Egyptian workers simply removed the ground itself.
After identifying granite obelisks and chipping away at the weathered upper layers, workers dug deep trenches all around the obelisk to undercut the rock and free it from the earth. Then, they cleared a path on one side so that it could be pushed out horizontally instead of lifted out vertically - a decidedly easier task.
Much of the evidence for these techniques comes from a famed "Unfinished Obelisk" that became abandoned midway through extraction.
Quarrying the rock-hard granite out of the earth and cutting it to shape is a difficult process even in the modern era, so archaeologists have long wondered how the ancient Egyptians managed to pull it off. The most compelling theories - backed by physical evidence - point to an ingenious method in which workers punched a series of holes in the rock with iron chisels, then stuffed those holes with wooden wedges.
The wedges were drenched with water, making them expand until they split the rock. Then, the Egyptians went to work on those fissures with their chisels until the granite got cut into a block.
Little documentation exists to explain how ancient Egyptians built the pyramids, but evidence that has survived to the modern era - including hieroglyphs and the papyrus diary of a worker called "Merer" - hints at a culture with a deep understanding of physics.
Through their advanced knowledge of the laws of the universe, the ancient Egyptians were able to take the same "simple machines" elementary school students learn about today and apply them on a grand scale.
They didn't need advanced technology to transport tons of granite across miles of desert - instead, they merely required the use of basic technology with creativity and ingenuity.