The ‘Grand Challenges’ of our times, like climate change, resource depletion, global inequity, and the destruction of wildlife and biodiversity can only be addressed by innovating cities. Despite the options of tele-working, tele-trading and tele-amusing, that allow people to participate in ever more activities, wherever they are, people are resettling in cities at an unprecedented speed. The forecasted ‘rurification’ of society did not occur. Technological development has drained rural society from its main source of income, agriculture, as only a marginal fraction of the labour force is employed in agriculture in the rich parts of the world. Moreover, technological innovation created new jobs in the IT and service sectors in cities. ...