Bangkok, Thailand
Number of projected overnight visitors: 20.19 million
For the second year running, Bangkok is set to be the most popular city for international travelers, thanks in large part to its appealing mix of historical sites and modern hot spots: the gilded Grand Palace complex, the towering Peninsula Bangkok, the canals and alleys filled with street food vendors—and that's just the start. Even with all that humidity, this city is showing no signs of slowing down any time soon.