1. Lots of people with lots of time on their hands did something that we'd be currently hard pressed to do but no one has really tried yet.
OR
2. Two aliens land on Earth and one of them says "Hey, how do we help out these poor savages to advance their civilization? I know, we'll teach them to build really cool walls from stone!"
...I know which one I'll pick. The wiki article doesn't offer any suspicions of extraterrestrial origin. In fact, a contemporary account suggests it's just hard work:
"to save themselves the expense, effort and delay with which the Indians worked the stone, they pulled down all the smooth masonry in the walls. There is indeed not a house in the city that has not been made of this stone, or at least the houses built by the Spaniards."
Or 3, some ancient people had better construction technology than we give them credit for. No need to bring up aliens every time someone questions orthodoxy.
Yes, there are many theories that can be entertained. My favourite is the mythos that, over a hundred thousand years, perhaps humans did evolve to the point they had technology to leave the planet, tidying up after themselves as they did, and its just us stragglers left behind that have been slowly devolving the tools they also left behind .. 'what if' doesn't have to be disregarded, just because its preposterous.
I mean, I never once mentioned two aliens in a UFO, but hey .. sure, why not.
I think people tend to overestimate progress. Skyscrapers happened a hundred years ago with advent of elevators. I've visited some Roman cites, they are massive. They had five storey residential buildings - just like these days.
1. Lots of people with lots of time on their hands did something that we'd be currently hard pressed to do but no one has really tried yet.
OR
2. Two aliens land on Earth and one of them says "Hey, how do we help out these poor savages to advance their civilization? I know, we'll teach them to build really cool walls from stone!"
...I know which one I'll pick. The wiki article doesn't offer any suspicions of extraterrestrial origin. In fact, a contemporary account suggests it's just hard work:
"to save themselves the expense, effort and delay with which the Indians worked the stone, they pulled down all the smooth masonry in the walls. There is indeed not a house in the city that has not been made of this stone, or at least the houses built by the Spaniards."
https://en.wikipedia.org/wiki/Sacsayhuam%C3%A1n
EDIT: Do you have a reference for the 0.005mm precision claim? Some of those walls look impressive but the pictures I'm looking at, definitely don't suggest such God-like precision: https://en.wikipedia.org/wiki/Sacsayhuam%C3%A1n#/media/File:...
https://en.wikipedia.org/wiki/Sacsayhuam%C3%A1n#/media/File:...