Well I've made some calcs and we will be 250 hammers short for the Pyramids at 500 BC. That make them impossible for city #3 for sure.
And look at Qin land - his cows and horse are builded again, he has a mine, forest and his 5pop capitol is on plain hill : 3+4+3+1+2 = 13x50%= 19. And this is on the save turn while we must to settle, build workers, build mines, connect the stone and so on and at the end we will have 16 hammers.
Also he could started the the pyramids before few turns.
IMO the Pyramids are sure big pile of gold from this point.
And look at Qin land - his cows and horse are builded again, he has a mine, forest and his 5pop capitol is on plain hill : 3+4+3+1+2 = 13x50%= 19. And this is on the save turn while we must to settle, build workers, build mines, connect the stone and so on and at the end we will have 16 hammers.
Also he could started the the pyramids before few turns.
IMO the Pyramids are sure big pile of gold from this point.