@vietnamtodayvtv: Ngườm Ngao Cave: a hundred-million-year masterpiece Hidden beneath the limestone mountains of Cao Bằng, Ngườm Ngao Cave is a 400-million-year-old geological wonder. Discovered in 1921 and opened to tourism in 1996, its relatively late discovery helped preserve much of its pristine beauty. Today, the cave features both a traditional sightseeing route and a new adventure route. #VietnamToday #NguomNgaoCave #CaoBang #Geology #NaturalWonder #LimestoneCave #AdventureTravel