This third issue of Cogito opens with a feature on the fundamental challenges that metropolises are facing around the world with regard to the environment, housing, diversity, security, new technologies, etc. Be they are chronic or recent these issues are at the heart of changing power relations. They are explored in many innovative analyses by Sciences Po researchers that are presented here. This issue also delves into the latest publications and research projects, and introduces promising recent PhD graduates. Wishing you a good start to the school year and a good read!