Name: Colonial Hanoi
OUV: Main parts of Hanoi follow French city planning making Hanoi into a very different Asian city. Even Gustave Eiffel built here.
"Embarked on a grand mission civilisatrice, the French colonial administration laid wide, tree-lined boulevards patterned on the Champs Élysées, installed electric lights and built villas in a hybrid style known as Norman Pagoda"
"Some of the street scenes in Hanoi could be Paris. The French-style mansions and tree-lined boulevards help retain the city's reputation as being "The Paris of the East". Hanoi's culture, however, is uniquely Vietnamese and it exhibits few of the scars of the Indochina War."
We could also include the Vietnamese heritage of the city, e.g. the central lake.Name: Ba Be National Park
OUV: Caves, Karst Mountains, Mountain Tribes, Waterfalls, Lakes, Jungle.
"Ba Be National Park is considered as the most important and meaningful natural habitat for biodiversity conservation and it is also a home of many rare endangered flora and fauna. The forest cover of Ba Be contains a typical sample of limestone vegetation and is scarce in other countries in the region."http://whc.unesco.org/en/tentativelists/6262
"Ba Be Lake or Ba Be National Park is located in Bac Can Province, 240km from Hanoi and covers more than 23,000 hectares boasting waterfalls, rivers, deep valleys, lakes and caves set amid towering peaks. The area is home to many ethnic minority communities."https://wikitravel.org/en/Ba_Be_National_ParkName: Ban Gioc Waterfall System
Country: Vietnam, China
OUV Amazing lush karst mountains with farms, caves and a huge waterfall. Can be combined with more waterfalls on the Chinese side.
"Over thousands of years the waterfall has eroded its crest and slowly moved upstream. It currently appears to be two waterfalls most of the time but when the river is swollen due to summer rains can form one fall again."https://en.wikipedia.org/wiki/Ban_Gioc%E2%80%93Detian_Falls
"Ban Gioc Waterfall or Thac Ban Gioc located in Cao Bang province, 350km from Hanoi is one of 4 biggest waterfalls located on a frontier after Iguazu, Victoria and Niagara. The area is home to many ethnic minority communities, such as the Nung, Dzao and H'mong ethnic groups. B"https://wikitravel.org/en/Ban_Gioc_WaterfallName: Mekong Delta
OUV: Swimming markets, river islands, ...Further suggestions
Coffee Plantations of Vietnam -> #2 World Wide Producer.
French Railway Hanoi Saigon.https://en.wikipedia.org/wiki/Rail_transport_in_Vietnam#Current_lines
More traditional villages all over the country -> So many local people living in traditional villages.
Mountain Villages of Sapa (Vietnam) -> Very popular area, but can't find a most viable candidate. There is a separate tentative site for archeological finds, but I would rather go for the villages.
Dalat Wine Region - ;)