Together with Nahuel Huapi National Park in Patagonia, it is one of the most frequented tourist sites. In guarani language, the term "Iguazú" means "great waters". It was discovered in 1541 by Alvar Núñez Cabeza de Vaca and established in 1984 as Natural World Heritage Site by UNESCO. Situated in Iguazú National Park, some 20 km. from Puerto Iguazú in the north of the province, these falls are shared by Brazil and Argentina. Iguazú river is born in Paraná state in Brazil, and after crossing 1,200 km. on a plateau where it receives several affluents, it reaches a fault forming a crack in the interleaved layers of sandstone and basalt where the river runs.