actually the Egyptian pyramids being built by slaves is highly argued and confused topic. the truth is noone knows for sure if they were slaves.

i think they were a class of people created by the pharaohs as masons. each man was a highly skilled individual; in different phases of construction. there's the masons themselves who quarried the massive blocks, then there's the architects who oversaw the placement of the stones. there are the stone carving artists who decorated the walls etc. and there are the people who actually moved the blocks. these i believe were not slaves but willing class of workers/subjects/worshipers and genuinely believed that their work was for the pharaohs passage into immortality thus gaining them favor in the eyes of the future eternal god.