How did they build such precision into Peruvian stone walls?

Here is one solution for the continuing enigma of Peruvian precision stone carving, which resembles puzzle pieces (or dozens of soap bubbles) more than modern bricklaying. The solution has to be simple, given the tools of the time.

Figure 1. Short segment of a Peruvian stone wall with precision stone carving. One solution is to first create this as a precisely carved street, then disassemble it and reassemble it vertically to create the wall.

The carving-lifting-fitting-carving-lifting-fitting problem
on a vertical wall with cranes and ropes (see video below) is resolved if you first carve and fit the stones that make up the wall horizontally on a flat surface. That’s all you have to do: first create a paved ‘street’. Treat the whole wall as a unit. In that way large stones can be set among smaller stones for design effects. Notches and curves can be created between every stone pairing. Dozens to hundreds of stone masons can be working on all the stones at once. A single overseer can guide their efforts. As the edges are carved off, the stones gradually get closer and closer to one another.

At that point,
when everything fits precisely as a horizontal puzzle, workers can then disassemble the horizontal ‘street’ and confidently re-erect each pre-carved stone atop one another creating a vertical wall with hyper precision already built in.

1. Each wall is created as a unit
2. Precision cuts are made into stones when they are all easily manipulable—on the ground, until they can be pushed together without any air between them.
3. No lifting, testing, re-lifting, retesting is required on a single stone trying to fit atop the wall, as in traditional thinking dictates
4. Once the wall is erected, you can’t go back and redo the operation. That explains why the stones later set on top of the precision set stones (on some walls, not present in figure 1) do not have the same precision of fit.
5. Not sure yet why some stones have small single or dual bumps near the bottom edge (not present in figure 1).