National Geographic : 1913 Apr
Photo by Hiram Bingham AN EXAMPLE OI EXTRAORDINARY STONE-CUTTING: MACHU PICCHU Connected with the semicircular tower is an ornamental wall made of specially selected blocks of beautifully grained white granite. The interior of the wall was ornamented by a series of symmetrical niches, between each one of which is a projecting stone roughly squared (see page 471). Photo by Hiram Bingham REMARKABLE NICHES AT MACHU PICCHU Another portion of the interior of the ornamental wall. Bear in mind that the ancient builders had no T squares nor right lines, and could approach straight lines only by the skill of a trained eye (see also page 488).