My favourite writer about cities, and a favourite of generations of my students, is Jane Jacobs, a sharp-tongued critic whose polemics were grounded in a strongly positive view of cities. She wrote her best-known book, The death and life of great American cities, when she was a New Yorker, but within a few years she had moved to Toronto, where she spent the rest of her life.

She loved cities and thought that the preservation of their livability and attractiveness was a key to the well-being of society as a whole. It’s central to Jacobs’s concept of cities that they are natural, that they grow organically out of the ways people choose to interact with each other.

As a result, in Death and life, she was scornful of the visions of planners and architects who wanted to create buildings, neighbourhoods, and parks in response to their ideas of…