10 most difficult Vietnam riddles

Ho Chi Minh City is the largest city in Vietnam. Under the name Saigon, it was the capital of the French colony of Cochin-china and later of the independent republic of South Vietnam from 1955–75.

The waters of river are indeed reddish because of the large amounts of red silt.

Hang Sơn Đoòng is a solutional cave in Phong Nha-Kẻ Bàng National Park, Vietnam near the Laos-Vietnam border. Its total length is approx. 9 km and its main passage is the largest known in the world, being more than 5 km long, 200 m high and 150 m wide. It was discovered in 1991 and the first tourist group explored the cave in 2013.

Most of the Vietnemese (around 45%) follows traditional folk beliefs. The other popular religions are Buddhism (around 16%) and Catholicism (around 8%). Many of Vietnamese consider themselves to be atheist (around 30%).

The Flag Tower of Hanoi (Vietnamese: Cột cờ Hà Nội) is a tower in Hanoi, Vietnam, which is one of the symbols of the city and once a part of the Hanoi Citadel, a World Heritage Site. Its height is 33.4 m. The tower was built in 1812 during the Nguyen dynasty as an observation post to the Hanoi Citadel. It is now located in the Vietnam Military History Museum

The Pagoda of the Celestial Lady is a historic temple in the city of Huế in Vietnam. Its iconic seven-story pagoda is regarded as the unofficial symbol of the city, and the temple has often been the subject of folk rhymes and ca dao about Huế.The pagoda sits on the Hà Khê hill, in the ward of Hương Long in Huế.

Mauritius papeda is a citrus fruit native to tropical Asia. Its rind and crushed leaves emit an intense citrus fragrance, and are used in many Southeast Asian cuisines such as Thai, Lao, Cambodian and Vietnamese. The plant is also used in perfumery, and in some countries in traditional medicine.

Approximately forty percent of Vietnamese people have this surname. Many events in Vietnamese history contributed to the name's prominence. The Nguyễn Dynasty awarded many people the surname Nguyễn during their rule, and many criminals also changed their surname to Nguyễn to avoid prosecution.

Words "four" and "Death" have very similar pronunciation in Chinese, Vietnamese, Korean and Japanese. In East Asia many buildings do not have a 4th floor. Some high-rise residential buildings omit all floor numbers with "4", e.g., 4, 14, 24, 34 and all 40–49 floors.

The four largest cities in Vietnam are Ho Chi Minh City (8.2 million), Ha Noi (7.4 million), Hai Phong (1.9 million) and Can Tho (1.2 million).