This essay introduces rules for building new urban squares, and for fixing existing ones that are dead. The public square as a fundamental urban element behaves both as a node and as a connector of the urban fabric. Like the components of an organism, each urban element is itself highly complex, and this conception contradicts postwar design trends based on abstract simplistic ideas: those are imposed in order to control instead of stimulating social life. Urban structures, infrastructure, human beings, their activity nodes, and all their interconnections come together to form a “super-organism”, a complex and dynamic whole that is the city. This happens only when the geometry of the urban fabric is encouraged to develop in a living manner. The basic element of this “super-organism” is urban space that works with informational processes. In European culture, the square connects the local urban space with other squares, streets, and roads with a strong pedestrian use. A living city works through its connections to reach the properties of a “super-organism”.