The pyramids weren't tombs. They were some sort of electrical power plant. We can see the parts of the plant, but how the electricity was harnessed and projected is still a mystery.
Granted, we know that some of the giant stone blocks were transported from a quarry, but it's likely that the problem of moving heavy blocks to the top was solved by making the blocks out of a natural form of concrete. In his books The Pyramids and the sequel Why the Pharaohs Built the Pyramids with Fake Stones, Joseph Davidovits builds a compelling argument for cement blocks. These blocks were made with sand from the wadi of the Nile and mixed with some herbs that, when hardened, would result in a block that looked identical to natural limestone. This slurry was carried in buckets to each new level of the pyramid and poured into a container framed by papyrus paper and wood. When the mix dried, the wood was removed on the outside of the container. The papyrus separating it from the other blocks disintegrated over time, leaving those impossibly thin lines between the blocks.
Davidovits actually made small blocks in a lab using these same materials and the result was indistinguishable from natural limestone millions of years old.