Source: WTL photo taken from the site of Sacsayhuaman.
Comments: This image illustrates huge size and weight of these megalithic limestone building blocks, and it also demonstrates the precision with which pre-Incas and Incas cut and shaped the stones. They are shaped so perfectly that a piece of paper will not fit anywhere between them. Note also the expertly crafted rounded corners at the end of the wall. Paleo-engineers have calculated that architect-builders designed the walls first; then the stones were cut in the many shapes you see here so that they would interlock perfectly; and finally they were lowered into place from a ramp and logs as levers. Power was supplied by humans.