Shenzhen, China, is the fastest-growing wealth hub in the world, home to 50,800 millionaires, 156 centimillionaires, and 22 billionaires.

But the Shenzhen to Chongqing and Shanghai to Chaohu (an ancient city in Hefei) routes have been the most popular over the last 11 days, according to the map. Tourist attractions are graded by how ...