<P> Thousands of tourists walk the Inca Trail to visit Machu Picchu each year . They congregate at Cusco before starting on the one -, two -, four - or five - day journey on foot from Kilometer 82 (or 77 or 85, four / five - day trip) or Kilometer 104 (one / two - day trip) near the town of Ollantaytambo in the Urubamba valley, walking up through the Andes to the isolated city . </P> <P> Machu Picchu is a UNESCO World Heritage Site, both cultural and natural . Since its discovery in 1911, growing numbers of tourists visit the site yearly, reaching 400,000 in 2000 . As Peru's most visited tourist attraction and major revenue generator, it is continually exposed to economic and commercial forces . In the late 1990s, the Peruvian government granted concessions to allow the construction of a cable car and a luxury hotel, including a tourist complex with boutiques and restaurants and a bridge to the site . Many people protested the plans, including Peruvians and foreign scientists, saying that more visitors would pose a physical burden on the ruins . A no - fly zone exists above the area . UNESCO is considering putting Machu Picchu on its List of World Heritage in Danger . </P> <P> During the 1980s a large rock from Machu Picchu's central plaza was moved to a different location to create a helicopter landing zone . In the 1990s, the government prohibited helicopter landings . In 2006, a Cusco - based company, Helicusco, sought approval for tourist flights over Machu Picchu . The resulting license was soon rescinded . </P> <P> Authorities have struggled to maintain tourist safety . Tourist deaths have been linked to altitude sickness, floods and hiking accidents . UNESCO received criticism for allowing tourists at the location given high risks of landslides, earthquakes and injury due to decaying structures . </P>

Machu picchu was a fortress for the incas