Chengdu, China has surged in population in the last few decades, from 8.2 million in 1980 to over 21 million today. It is one of several emerging megacities to boom under China’s “Go West” policy, which boosted economic development and migration to its previously underdeveloped interior. Chengdu’s metropolitan area has expanded outward with a series of concentric ring roads, spanning 1,760 square miles (4,559 square km). 30.660000°, 104.063333° Source imagery: Google Timelapse