A number of alternative theories have been proposed to explain how the Great Pyramid was built.
There is disagreement on whether the blocks were dragged, lifted, or even rolled into place.
The casing stones of the Great Pyramid and Khafre's Pyramid (constructed directly beside it) were cut to such optical precision as to be off true plane over their entire surface area by only one-fiftieth of an inch.
They were fitted together so perfectly that the tip of a knife cannot be inserted between the joints even to this day.
An estimated 2.4 million blocks were used in the construction.
High quality limestone was used for the outer casing, with some of the blocks weighing up to 15 tons.