Machu Picchu is Peru's top tourist site—and in fact is one of the world's most visited sites, attracting 1.3 million visitors in 2013 alone. It’s proven so popular that the Peruvian government is now investing in a plan to preserve the site, which is in danger of being worn down by tourist footfall. The plan will aim to limit the amount of wear and tear on the site. Machu Picchu is one of the most important Inca sites still existing in the world. Built in the 1400s, many archeologists believe the UNESCO World Heritage site was constructed as an estate for an Inca emperor. It lies around 50 miles from the city of Cusco.