Cities are places of mixing and meeting - places where different worlds encounter one another on the streets. Yet cities are all too often seen as unruly places in need of government and control. This work asks questions about the ways in which cities mix different worlds. Taking a fresh approach to issues of order and disorder and extending spatial understanding of cities, the book develops insights into city life, using a variety of examples drawn from around the world. It challenges the common-place assumption that cities are threatened by disorder from below and that they might be ruled by an order imposed from above. In fact, as this book shows, cities are open to many forms of order and disorder, from both within and beyond the city. Here are to be found cities' problems - and their potentials.