Walking in urban spaces is a central motif in the work of Belgian artist Francis Alÿs, who transforms the metropolis into a performative space through his urban interventions. In comparison with positions from the 1960s and 70s, including Richard Long, Allan Kaprow, and Gordon Matta-Clark, it becomes evident that contemporary art can be seen as undergoing a fundamental shift in the understanding of sculpture and space. Against the backdrop of the spatial turn paradigm, Ursula Grünenwald analyzes selected works by Francis Alÿs from 1990 to 2008 and examines the interplay of material, volume, and urban processes. Unlike existing research, she places his work within a spatial theoretical perspective and distinguishes various strategies of space activation and constitution: object-related actions, linear interventions, and social interactions.