Towering more than 650 feet, El Peñón de Guatapé (The Rock of Guatapé) is an inselberg, which is geologist-speak for a stone monolith that stands alone amid relatively flat surroundings. This huge rock is found in northwest Colombia, a region once inhabited by the Indigenous Tahamí people, who are said to have worshipped El Peñón, as many locals now call it. Probably because it"s so smooth, no one is known to have climbed the rock until 1954, when a small group of friends scaled it by wedging a series of boards into a vertical crack. It took them five days to reach the top.