There has been a profusion of work in recent years exploring the links between infrastructure and the city. This has entailed a conceptualization of cities and infrastructure that recognizes their mutual constitution and the inherently political nature of networked urban infrastructure. In introducing this symposium, we find that a comparative approach to infrastructure can reveal a diversity of ways in which the urban fabric is produced, managed and distributed, and comes to matter in everyday life. We argue for a more globally informed conceptualization of the politics of infrastructure by exploring three key themes in the symposium: fragmentation, inequality and crisis.