In May 2007 the world turned from being inhabited by a mainly rural population to a predominantly urban planet. Increased urbanization has been a trend all through last 200 years of industrialization and globalization and it does not seem to stop. Whether this trend is good or not for sustainable development has been debated over the years. The 1970s was a period when many environmentally aware people left the cities to live closer to nature. Today, however, the urban scenario appears increasingly attractive from a sustainable development point of view as it enables efficient solutions with regard to e.g. transport, energy, waste management, health care and education – and leaves more room for other species on the planet.