China faces challenges in urbanization

Once a backwater in China's often overlooked west, the city of Chongqing in the last two decades has been transformed into a sprawling metropolis where skyscrapers stretch endlessly along the Yangtze River.

Carved out of Sichuan province as a municipality in 1997, creating an area the size of Scotland, it now has a population of about 30 million, two-thirds of whom are farmers.

As of 2011, about a fifth of the urban center's population of 7 million are migrants from outside of the city.