Cities aren’t merely back. The biggest are now more sought-after than ever before. Manhattan and even crime-hit downtown Chicago have exceeded their pre-pandemic populations. London now probably has more than nine million inhabitants, its highest number ever. Greater Paris has a record 12.4 million. Cities such as Miami, Singapore and Berlin are becoming unaffordable. At the same time, global tourism is back with a vengeance.

Think of today’s city as a cramped flat. With space in such demand, we need to optimise the use of every square inch. Space management always becomes an urban art form in boom times. In Berlin during the Industrial Revolution, for instance, Schlafg?nger (roughly meaning “sleep-goers”) rented beds during the day while the primary occupants of apartments were at work.

But this art was forgotten when cities declined after the war and space became ample again. On the bombsites of 1960s London, writes Oliver Bullough in Moneyland, “shattered buildings that once housed trade and commerce grew abundant crops of rosebay willowherb, and provided playgrounds for wild children”. It took until 2015 for London to regain the peak population of 8.6 million that it hit in 1939.