A sustainable city is not only a city where the air is clean, waste is recycled, motor traffic is reduced, and ecological questions are central to city planners, but it is also a city that creates opportunities for its citizens to live healthy lives. This consideration includes prioritizing planning for physical activity, a central focus in this chapter. In particular, in this chapter, I discuss how physical activity and sport in public spaces can serve as tools for making cities more sustainable, with a particular emphasis on Swedish cities.