As I've read it, the large pyramids in Egypt literally involve millions of the large stone blocks they're made of.

Most assume that those blocks were carved from stone quarries in-situ. I see an overwhelming problem with that. You would waste more stone than you would use and the quarry itself would very quickly turn into a big hole filled with rubble.

Here is what I believe had to have happened. There was a train of wagons being pulled by large animals, elephants or oxen or some such. Those wagons were being filled with with stone rubble and rocks of some appropriate size and hauled to the pyramid build site; the rocks and rubble were being dumped into formers made of whatever passed for plywood in that age until the formers were more or less full; and then some liquid bonding agent was being poured into the former... I.E. the blocks werre being poured and not carved. Once a certain number of such blocks had been thus formed, the existing blocks could be used as one or two sides of the former for the next block, thus the observed tight fits.

A French scientist, Joseph Davidovits, who has studied this kind of thing uses the term geopolymer. e.g.

https://www.geopolymer.org/archaeology/pyramids/pyramids-2-the-evidences/

Charles Ginenthal also claimed that ancient Egyptians had technologies for liquifying and resolidifying hard stone such as diorite, and some effort has been made to reclaim that technology. Success in such an endeavor could result in roads that would last more or less forever.