A relic in Hanoi.

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The four cities of Vietnam in the list are Hanoi, Ha Long, Hoi An and Ho Chi Minh City.

Hanoi (14th): The charming Vietnamese capital has aged well, preserving the Old Quarter, monuments and colonial architecture, while making room for modern developments alongside. Hanoi may have shrugged off several former names, including Thang Long, or "ascending dragon," but it hasn't forgotten its past, as sites such as Ho Chi Minh's Mausoleum and Hoa Lo Prison attest.

Lakes, parks, shady boulevards and more than 600 temples and pagodas add to the appeal of this city, which is easily explored by taxi.

Hanoi flagpole.

One-pillar Pagoda.

The Temple of Literature.

The Huc Bridge.

Ho Chi Minh City (15th): Vietnam's bustling largest city sets the cultural and economic pace for the country. The former Saigon boasts charming French colonial architecture and wide boulevards, usually thronged and choked with traffic.

Taxis are an option for seeing the sprawling city. The War Remnants Museum shows the Vietnam War through Vietnamese eyes. Don't miss the impressive Jade Emperor Pagoda. Go to the frenetic Ben Thanh Market for cooking, flowers or frogs. Tour through the Mekong Delta, past rice paddies and houseboats.

Saigon Notre-Dame Basilica.

Vam Sat tourist site.

HCM City Theatre.

Hoi An (17th): This city on the central Vietnamese coast is a well-preserved example of the important Southeast Asian trading port it was from the 15th-19th centuries. Already a common stop for backpackers, it is becoming better known to tourists. On the 14th day of each lunar month, the town trades its electric lights for traditional colored lanterns. Sights include the Japanese Covered Bridge and the Quan Cong Temple. Let the town’s expert tailors make you some bespoke clothing.

Ha Long (25th): Travelers visit Hạ Long Bay in Ha Long City for an up-close look at its amazing limestone islands, rock formations and caves. Whittled away over centuries by wind and water, they’re breathtaking. Rent a kayak or a junk boat, or take a tour to explore.

The 21 other cities in the list include: Bangkok of Thailand; Tokyo and Kyoto of Japan; Hong Kong, Xi'an, Beijing and Shanghai of China, Siem Reap and Phnom Penh of Cambodia, Chiang Mai of Thailand, Singapore; Male in Maldives; Ubud in Indonesia; Seoul of South Korea; Taipei in Taiwan; Mumbai, New Delhi and Goa in India; Kathmandu in Nepal; Luang Prabang in Laos; Jaipur in India

Vietnamnet