The Pyramids at Giza are an engineering marvel from Egypt’s Old Kingdom period. The largest, the Great Pyramid, is 455 feet high and was constructed from approximately 2.3 million blocks weighing 2.5 tons each. There are many theories as to how the pyramids were built using primitive technology.
The External Ramp TheoryShow moreShow less
Evidence found at Giza supports the claim that at least some ramps were used. Ramps are commonly found in Egypt supporting other smaller pyramids and monumental structures. There are many variations on this theory. It is the most popular among archaeologists.
A zigzagging ramp would fit with the evidence with have from Giza and other sites that ramps were used. Unlike a long ramp model, it would have been compact and allowed for easy access up the face of the Pyramids.
Like other ramp explanations, this theory fits with the existing evidence found at other pyramids that ramps were used in construction, and with the writings of Diodorus Siculus. 
In order to create a ramp on one side which takes up minimal space, a ramp that zigzags back and forth down one face could have been used. The ramp would be constructed as the pyramid grew and would need to zig-zag at least seven times to reach the top and remain at a sensible gradient. In the event that a zig-zag ramp was used on all four faces, the operation would have moved quite quickly compared to a long ramp model.
A zig-zag ramp accounts for the evidence of a small ramp at the Great pyramids base, and the lack of evidence for a long perpendicular ramp.
A zig-zag ramp accounts for the evidence of ramps but would have taken up minimal space, unlike a long ramp.
The zigzagging ramp model would have had particularly tight corners. Maneuvering the large 2-ton bocks around these corners even with leavers would have been very difficult and moving the 60-ton beams used in the king’s chamber would have been impossible.
The number of turns needed to keep a sensible gradient for the zigzag ramp would compromise the stability of the zigzagging ramp, which like the long ramp would end up being enormous and potentially unstable. Applying the limestone finish would be difficult with four huge earthworks covering the face of the pyramid.