Inca Trail to Machu Picchu along below the crest of the east slope of the mountain named Machu Picchu. The steep stairs leading to Inti Punku ("sun gate") are reached after approximately 3 km. Reaching the crest of this ridge reveals the grandeur of the ruins of Machu Picchu, which lie below. A short downhill walk is the final section of the trail. Because of its popularity, the Peruvian Government instituted several controls to reduce human impact upon the trail and within the ancient city. The most notable is a quota system, introduced in 2001, whereby only a set number of people (including hikers, porters,
Machu Picchu prevent it from running down the mountain. Similar layering protected the large city center from flooding. Multiple canals and reserves provide water throughout the city that could be supplied to the terraces for irrigation and to prevent erosion and flooding. The Incas never used wheels in a practical way, although their use in toys shows that they knew the principle. The use of wheels in engineering may have been limited due to the lack of strong draft animals, steep terrain and dense vegetation. The approach to moving and placing the enormous stones remains uncertain, probably involving hundreds of men to