The recognition was announced on Monday at a meeting of the Heritage Committee of the United Nations' Educational, Scientific and Cultural Organisation in Doha, Qatar.
The complex consists of three adjacent areas. These consist of the cultural area, the ancient capital of Hoa Lu (under three short-lived dynasties - Dinh, early Le and early Ly between 968 and 1009).
The natural aspects are the stunning limestone peaks, streams and caves at Trang An, Tam Coc and Bich Dong and Hoa Lu. Then there is the primeval forest. The whole complex covers 4,000ha and a buffer zone of beautiful green paddy fields.
The newly recognised Trang An complex meets UNESCO's three criteria for possessing cultural, aesthetic and geographical values.
Scientists recently found evidence of the continued interaction between early human beings and environment for at least 30,000 years, including their adaptation to rising seas at the end of the last Ice Age six to seven thousand years ago.
The complex offers magnificent scenery with karst mountains rising over streams of calm water. The mountains also hide many caves and pagodas.
The population has been recognized by UNESCO as cultural heritage and the natural world including eco-tourism destinations of Trang An, Tam Coc - Bich Dong, Bai Dinh Pagoda, the ancient capital of Hoa Lu (Ninh Binh).
Vietnam now has eight World Heritage sites: Ha Long Bay (Quang Ninh Province), Phong Nha Ke Bang National Park (Quang Binh Province), Hue Complex of Monuments (Thua Thien Hue Province), Hoi An Ancient Town, My Son Sanctuary (Quang Nam Province), Thang Long Imperial Citadel (Ha Noi) and Ho Citadel (Thanh Hoa Province).
Here are photos of the newly-recognized world heritage: