The world is moving into cities. By 2030 it’s estimated that 75 percent of people will be living in an urban environment. And that is going to put huge strains on the planet’s natural resources. It also means the way our cities develop is in need of a massive rethink. There are proposals to create enormous ‘Ecopolises’ such as those in Mazdar in the United Arab Emirates or Dong Tan in China. But would such creations be sustainable? Freiburg in Germany is a model functional eco-city, recognised as Germany’s “Greenest City”, and is imitated all over the world. But Freiburg is not a new city. In the late 1970s, when the German government announced plans for a nuclear power station in the area, its citizens revolted, staging protests and strikes until the plans were defeated. So the people of Freiburg set about developing new and environmentally sound methods of supplying their energy. From this grass roots movement, the modern day eco-city of Freiburg was born.