Machu Picchu is an Inca citadel set high in the Andes Mountains in Peru, near Cuzco. It is located over 8,000 feet above sea level and was built in the 15th century, but abandoned a century later at the time of the Spanish conquest of the Inca Empire. The ruins were rediscovered in 1911 by American historian Hiram Bingham. Today it is one of Peru's most popular tourist attractions, though visiting requires strenuous hiking at high altitude and tourism has caused environmental impacts to the surrounding area.