Datong, China

With a population of over 3.1 million, Datong is a small city by Chinese standards. However, this northern coal mining hub is hardly a picturesque destination. The brutal winters and heavy air pollution are persistent headaches, while the local government's aggressive redevelopment efforts have left much of the historic old town in a state of disrepair. Despite boasting attractions like the renowned Yungang Grottoes, Datong's gritty industrial character and complex bureaucracy make it a poor fit for all but the most adventurous expats. This is a city for the resilient, not the faint of heart.