It is possible to present a credible picture of urbanisation as one of the greatest threats to human health, wellbeing and development, although this paper will argue that to do so requires focusing on a limited set of cities. There is a stronger evidence base on cities and urbanisation underpinning good health, fulfilment of civil rights, democracy and freedom from deprivation, although with important exceptions. It is possible to present urbanisation as the most serious driver of human-induced climate change (and of most other kinds of ecological damage). But cities also have the potential to be places where high living standards can be delinked from unsustainable ecological footprints and high greenhouse gas (GHG) emissions (and there are some cities that demonstrate this). Of course, a very different set of urban centres get highlighted, depending on which of these points one wants to substantiate. What this paper seeks to do is to highlight both the threats and the opportunities posed by urbanisation.