Back in my day I was told that slavery made it happen but I question this view as do many others now.
You see the main Pyramid of Giza is made of Granite blocks which have been precision cut.
The other pyramids are just made of limestone and such.
Well I think Over a long time they worked on fuels which could charge by the sun and a pyramid initially was used to reflect or refract the light into the bottom and cook up the top.
One of these fuels could produce electric enough electric eventually enough to to create a hovering carrying cart that balances on the earths electromagnetic field through a strong electro gravitational effect.
These Vehicles back then were not to sit on but to carry luggage and eventually large granite bricks as a demonstration of the technologies ability.
I don't personally think they went up the nile with these bricks how did they carry them off the nile on land anyways.