How can the "Good Life" (Buen Vivir) be promoted in the city? How can urban resilience be strengthened in a time of multiple crises? What does a district look like that will be designed by its own residents? This text examines the potential of an "intentional transformation towards sustainability", which is mainly bottom-up, driven by "unconventional alliances" (including between citizens and institutions) at the local level. The empirical source of knowledge for the analysis is a "real-world lab" in Cologne (Germany). Since 2013, the so-called "Day of the Good Life" (Tag des guten Lebens) takes place once a year. It is supported by a diverse local network of about 130 organizations and many dedicated citizens. This day isn't an event, but serve as a catalyst in a comprehensive process, that promotes trust and cooperation in the neighbourhood and makes a whole district to a commons. This process shows why a transformation towards sustainability isn't first a question of economic capital or of technological innovation, but of human and social relationships.