Serge Antoine, a high-ranking civil servant (Conseiller-Maître à la Courdes Comptes) who, among his other distinguished posts, has been responsible for international relations at the French Ministry of the Environment and originator of the Mediterranean Blue Plan, is President of the Claude Nicolas Ledoux Foundation for future-oriented studies, member of the board of the international association Futuribles, and member of the World Society for Ekistics (WSE). The text that follows is an edited, revised and expanded version of a paper presented at the WSE Symposion "Defining Success of the City in the 21st Century", Berlin, 24-28 October, 2001.