Machu Picchu is one of the most beautiful and enigmatic archaeological sites in the world.  Since its "discovery" in 1911 by Hiram Bingham III, it has been visited by several 100,000 tourists a year.  I traveled to Machu Picchu during the mid-1980's when the Sendero Luminoso were still very active in the region. They kept blowing up the tourist train. Added a whole new dimension to the experience [NOTE: Image was scanned from a slide].