Thien Duong (Paradise) Cave, labeled the world’s most beautiful and magnificent cave when it was discovered in the central province of Quang Binh in 2005, has been open to tourists since September 3. Located in the middle of Phong Nha-Ke Bang National Park, a UNESCO World Natural Heritage Site in Quang Binh, the cave was formed around 300-400 million years ago, surrounded by underground streams and rocky mountains.