When Charles Montgomery first started talking about urban happiness, people laughed at him. As his colleague Omar Dominguez explains, “happiness is kind of an out-there concept for some people”. Montgomery and Dominguez work at Happy City, a Canadian organisation named after Montgomery’s 2013 book, which makes the case for retrofitting cities for happiness and argues that streets, parks, shopping centres, housing estates – indeed most urban infrastructure – can be designed to make people feel…