Macchu Picchu is a fun rabbit hole to go down. Some of those stones are so massive, and have some very peculiar cuts...
Also, there are strong implications that the Incas inherited (or found) the ruins from an older, lost civilization. This "mystery civilization" were using a different technology that became lost to the Incas, the latter building on top of the megalithic stones in a haphazard, hopshod way with smaller stones.
How did they get such massive stones up such a steep, narrow mountain? Well, Shamanic Magic, of course!