Initially delivered as the 2017 CARGC Distinguished Lecture in Global Communication, CARGC Paper 12 presents an analysis of cities as complex, diverse, and incomplete systems. For Sassen, it is precisely these features of urban forms – their complexity, diversity and incompleteness – that offer the possibility of a new type of politics, centered on new types of political actors. She is particularly interested in two features of global cities: their presence as strategic frontier zones where actors from different worlds can meet without clear rules of engagement and their strategic importance for hacking old orders.