Its current name translates to "Lost City," but this mysterious ruin in Colombia's Sierra Nevada is also known as Teyuna and Buritaca. Founded in 800 CE, it predates the Inca city of Machu Picchu by about 650 years. It would not be rediscovered, though, until 1972. It seems to have been the central city in a network of villages built by the native Tairona people. It features terraces, a lattice of roads, and circular plazas. It might have been home to up to 8,000 people.