The fifth Bernardo Secchi Day of Study is jointly organized by three entities: the Braillard Architects Foundation, in the framework of its Culture and Research Programme The Eco-Century Projet ®; the Habitat Research Centre of the Swiss Federal Institute of Technology in Lausanne; and the Albert Hirschman Centre on Democracy of the Graduate Institute of International and Development Studies in Geneva. This day continues the momentum established during the critical commemoration of the Sarraz Declaration. Ninety years after the Second International Congress of Modern Architecture (CIAM, Frankfurt am Main, 1929), which set the goal of a minimum but dignified standard of living for urban populations under the term “existenzminimum”, we find ourselves in the midst of a debate on the conditions necessary for the habitability of urban territories. On the one hand, because the recurrent social demands are a reminder that no rights are guaranteed without citizen vigilance; on the other hand, because the ceiling of resources to be consumed on the “day of overspending” now meets with a broad consensus both among specialists and in civil society; finally, because the city and the local level now constitute the space in which it is possible to act to revitalize our democracies. Thus, the art of urban planning, closely linked to the art of governance, is confirmed as the search for a balance, a golden mean, an optimal spatial framework that could be described as “existenzoptimum”, as demonstrated in the recent work of the English economist Kate Raworth.