Shizuishan, China

With a population of over 750,000, Shizuishan is no sleepy backwater. This former caravan hub on the western bank of the Yellow River is an industrial powerhouse, fueled by coal, coking, and metallurgy. But the city's rapid growth has come at a cost - Shizuishan was once infamously described as the perfect setting for an "end of the world" film, thanks to its severe pollution problem. Despite efforts to clean up its act, the environmental toll remains a persistent headache for residents. Those seeking a quiet, pastoral life in China would do well to look elsewhere; Shizuishan is for hardy souls willing to brave the grit and grime of a rapidly industrializing frontier town.