Phong Nha Caves are a complex of 14 grottoes situated in a region of Limestone Mountains in Ke Bang National Park. The caves were listed as a World Natural Heritage Site in July of 2003 by Unesco. On the way we visit some of the most famous battlefields in the Vietnam War; Ben Hai River, Hien Luong Bridge, all lie in the Demilitarized Zone of the Vietnam war.