Tucked away in the Amazon forests, perched atop an Andean plateau, this ancient city is an architectural marvel. Often referred to as the 'Lost city of the Incas', it has been recognised as a World Heritage Site and one of the New 7 Wonders of the World. Built around 1450, at the height of the Inca empire, the entire city has been constructed using polished dry stone and has survived the centuries remarkably well. One of the three primary constructions within the city is the Intihuatana, a pillar built using stones that point to the sun. At noon on March 21 and September 21, the sun is almost directly above the pillar, and casts no shadow. It is believed that the Incas used this as a clock or calendar based on the sun's path. So for the traveller who enjoys a little history lesson along the way, Machu Picchu does just that.