8000 ft above sea sits Machu Picchu. Built around 1460, it was abandoned less than 100 years later after most if its inhabitants were wiped out by smallpox. Over the years, the surrounding jungle overgrew much of the site. On July 24, 1911, however,

a local 11 year old boy led historian Hiram Bingham up the mountain to the top of the site, bringing it worldwide attention.

Interestingly, smallpox is the only human infectious disease to have been completely eradicated. Good thing, too, since during the 20th century, it is estimated that 300-500 million people died from smallpox.

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