Today we know that the city is created and exists — also as built environment — as a result of action embedded in socio-material collectives. This is followed by an understanding of space as something co-produced everyday. The question “What is a city?” is no longer at the heart of the urban theoretical discourse, it is rather the question of performativity, “What makes the city?” This is due to new urban policy issues: How can we integrate rather than react, given the unpredictability of the city? How can urban life worlds no longer deform but perform? In this process, the view of action itself takes on a new form. If we comprehend how the city acts, as Bruno Latour noted, action can no longer be limited a priori to “what people do ‘intentionally’, ‘with meaning.” In order to read the urban as a process, a new model of action is needed. We propose the concept of improvisation — not as a last resort, but as a principle of the creation of and the navigating in the urban users’ transformational forms of being, in order to develop a technology of improvisation as an urban practice in the 21st century. An instructional format with lectures, performances, and bands.