The Choquequirao trail bends downward toward the Apurímac River in the Peruvian Andes. The trek, which leads to mysterious Inca ruins, is considered one of the most difficult in South America. Click the above image to enlarge, click to view my high-resolution photo gallery, or click to read my feature article “Peruvian Andes: The Violent Reckoning of Pax Americana.”