This chapter summarizes the concepts discussed in the course Cities and the Challenge of Sustainable Development. Jeffrey Sachs review the cross-cutting issues discussed in earlier chapters, including the importance of developing urban settlements into smart, shared spaces that foster creativity and knowledge growth. Using case studies, he provides further examples of how this is being done across the world and how these methods can be applied in the future. He stresses the significance of universities and centers of learning as places of great creativity and innovation towards the goal of building sustainable cities.