Colca Canyon Arequipa , Perú
This canyon is reportedly the deepest in the world, thought to be twice as deep as the Grand Canyon in the USA. Unlike most of the Grand Canyon, portions of the Colca canyon are habitable, with pre-Colombian terraced fields still supporting agriculture and human life. Click on this photo from Peru - Colca Canyon - Condor Pass, Part 2, Andrys Basten's Trip to Peru, for a very large photo which shows in wonderful detail how every bit of land is put to use. Then click to Part I and read her full account of her trip with more photos.