Inca Trail

The classic adventurer's route to Machu Picchu.  Originally the main route for the Inca between Cusco and the mountain citadel, today it's a four-day hike for many backpackers.  The trail from the most common starting point spans about 40km of hiking, with passes that climb up to nearly 14,000 feat above sea level.  Much of the trail itself is original Inca construction, so the Peruvian government has recently begun to place limits on the number of people allowed to travel along the route.

More photos can be found for the various archeological sites along the trail; see Runkuraqay, Puyupatamarka, Intipata, Wiñay Wayna, and Intipunku.