I saw the evidence of Inca engineering skill in the tour that took me to Machu Picchu.Only in hindsight, when I was preparing to write about it, did I begin to fully appreciate the Inca Empire's ...

Discovering Moray -- Civil engineering planning -- Inca technology -- Hydrology -- Hydraulic engineering -- Construction engineering -- Agriculture -- The Moray agricultural research station theory -- ...

This story appears in the April 2011 issue of National Geographic magazine. On the remote Peruvian island of Taquile, in the middle of the great Lake Titicaca, hundreds of people stand in silence on ...

Inca bureaucrats recorded all the goings-on in their bustling empire using knotted cords called khipu, where the position and order of the knots represented numbers. They relied on the khipu system to ...