Every building in Vauban has solar panels on its roof. It’s not surprising that Vauban is the greenest area of the greenest city, Freiburg, in the greenest province, Baden-Württemberg, in Germany. Freiburg, a city of about 220,000 people and 155 km2, is already known as an eco-city with the Green Party having the strongest presence there of anywhere in the country.