I was thinking more like the Egyptian pyramids, Pharoah watching over as the slaves move the bricks up there one by one,
It's quite likely the Pyramids (and other similar monuments) weren't built by slave labor. I mean, any more so than any other endeavor for that time and place. Many of the workers involved were skilled, and we've got tallies and receipts for wages for various people who worked on big construction projects like that.
And if you think about it, would it make sense for Pharaoh to buy a gajillion slaves, feed and house them in some way--even deliberately substandard rations would be a whole big mess of barley and onions--and then find some way to sell them off when the project was done? Or feed and house them until the next expensive architectural project? It makes very little sense.
It makes much better sense to hire laborers when they're available--say, agricultural downtimes--and pay them only while they work for you. Or, not uncommon for any number of ancient societies, require a certain amount of public labor from every family and use the corvee to do whatever's needed at that particular time.
And given what we know about Egyptian religion, I strongly suspect that it was a great deal more like the situation with European cathedrals, castles, etc. The laborers were almost certainly paid (barring assistants or indentured servants or bondsmen or what have you, who certainly existed in Medieval Europe, just like yeah, there were slaves in ancient Egypt and they were pretty much everywhere) and almost certainly believed in the worth of what they were doing--for the (G)god(s), for the institutions and ideologies they believed in, for their clan or region or country or tribe or whatever.
I'm sure there were slaves involved in the pyramids' construction, there were slaves all over the ancient world. But the popular image of thousands of hapless slaves building the pyramids is probably not terribly accurate.