The oldest, largest and most visited national park of the Republic of Croatia are the Plitvice Lakes, proclaimed a national park on April 8, 1949, and thirty years later listed on the UNESCO World Heritage List due to the unique universal value of the tufa formation process. The most attractive parts of the Park are the cascaded lakes formed by the biodynamic growth process of tufa barriers. These barriers remodelled what was once a river valley and enabled the creation of lakes which are connected by a series of waterfalls into a single water system. The tufa barriers continue to grow and thus constantly change the appearance of the lakes and waterfalls. Educational panels along the trail introduce visitors to the forest ecosystem and other natural features and sights.