When fields were cleared, the stones were stacked.

Stone walls twenty feet high run for miles, with wall on both sides of the routes through the hugh farms.

Contrast the Inca work with the current. The Spanish should be embarrased at destroying, root and branch, such a civilization.

Why go to the trouble of building in stone when one can make mud bricks. The only thing is that after a 1000 years, the Inca builds are still standing, while the mud ones and stone ones of the Spanish fall with every earthquake.