Originally built by the Incas, the manmade salt pans in Maras, Peru, have endured for over 500 years. Beneath the Qaqawiñay mountains runs a salty fresh spring, which empties into 3,000 mountainside pools. The sun heats them, evaporating the water and leaving the natural salt crystals behind. Each pool is still hand-mined, much the same as when the Incas were there. On this breathtaking hillside, it's easy to marvel at Mother Nature and the ingenuity of humankind.