The Intihuatana, or Hitching Post of the Sun, is the best known of the many sacred carved rocks and shrines of Machu Picchu, the ancient Inca ruins that lay hidden for 400 years until they were discovered by the Yale University archaeologist Hiram Bingham in 1911. Taken from Realm of the Incas by Max Milligan (HarperCollins, £29.99).