Halong Bay was designated a UNESCO World Heritage Site in 1994, but you'll feel the imprint of the millions of years it took to form as you swerve in and out of its limestone cliffs by boat. Pose for selfies with friendly locals into the streets of Ha Long City or Cat Ba Island, or hike up to Pho Tsi Mountain for a panorama you can enjoy from dry land.
Vietnam's capital Hanoi celebrated its 1,000th birthday in 2010, and even a short time in the city allows you to see a cross section of its impressive history. The Temple of Literature hosts Vietnam's first university, while Hoa La Prison tells the moving stories of the Vietnam War. The red hue of Huc Bridge, which crosses Hoan Kiem Lake, is timeless and iconic, while the ultra-modern Hanoi Museum, fashioned as an inverted pyramid, embodies the boldness with which Vietnam has entered the 21st century.