Machu Picchu is an Inca trail located in Peru atop the Andes mountains that was possibly built as a city for the early Incas in 1450. Considered an extreme tourist destination, Machu Picchu is also known as the "Lost City of the Incas" and sits above a loop of the Urubamba River, though it was abandoned around 100 years after construction when its population was wiped out by smallpox before the Spanish conquistadors arrived.