Meeting all audiences. The urban population continues to grow and will soon account for 80% of the world's population, against 50% currently. This demographic explosion, combined with the formidable ecological challenge facing us, but also with the very rapid change of our societies, will strongly impact the face of the cities of tomorrow. This public evening proposes to explore the future of our cities during the next century. Elected officials, urban planners, architects, sociologists and philosophers will try to define the challenges that we must solve and outline the possible future of our cities. This evening at the crossroads of science and imagination, illustrated live by Frédéric Malenfer, will end with a glass of friendship.