image creditNestled atop a mountain ridge in Peru, the 15th-century Inca city of Machu Picchu had sat largely forgotten for centuries - until archaeologist Hiram Bingham began excavations of the ruins in 1911. Now one of the most popular tourist destinations in the world, Machu Picchu's original purpose is still unknown - though many archaeologists think they are closer to finding an answer.
Here are some of the top theories about Machu Picchu proposed - and in some cases disproven - in the century since its 'rediscovery.'The Presurfer
