Hiram Bingham,
Inca Land: Explorations in the Highlands of Peru
“ How came it that so large a city as Piquillacta could have been built on the slopes of a mountain which has no running streams? Has the climate changed so much since those days? If so, how is it that the surrounding region is still the populous part of southern Peru? It is inconceivable that so large a city could have been built and occupied on a plateau four hundred feet above the nearest water unless there was some way of providing it other than the arduous one of bringing every drop up the hill on the backs of men and llamas. ”
