At night, when the sky clears, it's not difficult to guess where the bridge leads. The clouds on the other side of the bay glow orange, illuminated by the city of Hong Kong, with its population of 7 million, just beyond the horizon. Another glow can be seen farther north: the high-tech boomtown of Shenzhen, with 13 million inhabitants. There is a third and fourth patch of light in the sky even beyond that: Dongguan, with 8 million people, and Guangzhou, population 15 million.
