Tucuruí, Brazil

The population of 91,306 is a sobering statistic - this is no quaint backwater, but a sprawling Amazon city with all the attendant challenges. The Tucuruí Dam may provide power to 13 million people, but it has also displaced up to 35,000 residents, many of whom were shunted into inadequate new housing. Bureaucratic headaches are a persistent issue, as anti-dam activists have long protested the environmental and cultural destruction wrought by this engineering behemoth. While the dam has created close to 2,000 industrial jobs, the overall influx of people has strained Tucuruí's infrastructure. This is a city for the hardy, not the faint of heart.