From my reading in this area, these stones weighed 6-10 tons for the lower layers, and 1-2 tons for the upper layers. The pictures that we have show workers dragging stones on wooden sledges. Moving a 1 ton stone would probably take dozens or even hundreds of workers, depending on the friction and angle of the incline. My understanding is that most scholars believe that the Egyptians built dirt ramps, which were used to drag the stones up to the final location on the pyramid.

But I see some fundamental problems with the dirt ramp theory. I think there are two possible ways to do this, both of which have major challenges:

1. Spiral ramps that wrap around the pyramid. The problem that I see here is that it seems physically impossible to pull a sledge around a corner. As you get closer and closer to the corner, there is less and less room for the laborers to pull on the ropes, which means you can't use your full labor force to keep dragging the sledge up the dirt ramp. There's a couple of engineering options here, you can build ramps or wooden scaffolding to stick out past the corner, so the workers can keep pulling forward until the stone itself is at the corner. Or, you can have some type of giant wheel (similar to a capstan) that allows the workers to pull at a 90 degree angle and lets the ropes wrap around the pyramid. The first option would take a prohibitive amount of dirt (or a knowledge of scaffolding that's not supported in the written records). The second option would require the Egyptians to understand wheels and pulleys, which I thought that they didn't use.

2. Build one giant ramp that leads all the way to the top of the pyramid, in one straight shot. With the fairly gentle slope required by the sledges, I think this ramp would be ridiculously long. I don't know the exact angle of inclination that can be supported here, but modern trains max out at 2-3% and it's rare to see an ordinary paved road at more than 7-8%. If you have a 5% ramp angle, this means that the 140m pyramid would need a ramp that's almost 3 km long! That seems ridiculous to me. Even if they had enough workers to support a 10% ramp, this is a 1.5 km ramp, which is an incredible amount of dirt (far larger than the volume of the pyramid itself).

I have an engineering background, not a historian, so I understand the physical challenges far better than the history. Can somebody please weigh in on how this was actually physically possible?