Machu Picchu
Jean-Pierre Protzen proved the Verrills wrong. He went to Cuzco and
showed how river rocks could be used as hammers to pound stones into the
desired shape.
"It appears that the Inca technique of fitting the blocks together
was based largely on trial and error. It is a laborious method, particularly
if one considers the size of some of the huge stones at Sacsahuaman or Ollantaytambo.
What should be kept in mind, however, is that time and labor power were
probably of little concern to the Incas, who did not have a European notion
of time and had plenty of tribute labor from conquered peoples at their
disposal."
Jean-Pierre Protzen ---Scientific American ---Feb. 1986