Plitvice Lakes National Park (Nacionalni park Plitvička jezera) is the oldest national park in Southeast Europe and the largest national park in Croatia. The national park was founded in 1949 and is situated in the mountainous karst area of central Croatia, at the border to Bosnia Herzegovina. The protected area extends over 296.85 square kilometres (73,350 acres). In 1979, Plitvice Lakes National Park was added to the UNESCO World Heritage register among the first natural sites worldwide. (via)
I visited the Lakes after more than 30 years again and can tell that I was even more impressed than as little child. One feels simply overwhelmed by the masses of water and nature.