Eve Annecke and Mark Swilling returned last week from a month in Freiburg, Germany, commonly known as the ‘solar city’ of Western Europe. Governed for many years by the Green Party, Freiburg has steadily invested in sustainable infrastructures that have over the years transformed it into one of the most sustainable developed country cities in the world. This includes solar and wind power, but also in public transport (tram, bus, rail) and dedicated lanes for cyclists. This has also stimulated a unique knowledge economy as large research institutes and hi-tech industries have co-located in Freiburg because the values and brand of the city correspond to the purpose of these institutes and industries. It has become a global hub for sustainability innnovations that support thousands of jobs. Eve Annecke and Mark Swilling were guests of the University of Freiburg where they gave lectures on the MSc in Environmental Governance – a new transdisciplinary programme that is very similar to the Masters Programme in Sustainable Development that is delivered by the partnership between the Sustainability Institute and the School of Public Management and Planning. However, the main purpose of the month-long stay in Freiburg was to make progress with the writing of a new book called Just Transitions: Explorations of Sustainability in an Unfair World. Co-authored by Eve Annecke and Mark Swilling, this book will be published in 2010 by local and international publishers. The key chapter completed while in Freiburg (Chapter 5) was on the challenge of building sustainable cities – Freiburg was an appropriate place to be inspired to write about the future of cities.