Paris is known as “the capital of the 19th century”, and day to day, it feels like it. I live on a 19th-century Haussmannian street. I travel around on a late 19th-century invention, a bicycle with two equally sized wheels, when I’m not using the prehistoric technology of walking. Living here has helped me realise: the 20th century was rubbish for cities. All over Europe, in particular, cities are now peeling off the century’s imprint like a bad wallpapering job in ways that go beyond pushing out cars. The post-pandemic urban ideal is a cleaned-up version of the 19th-century city with 21st-century enhancements.

Early last century, cities made some fateful bad choices. Offered two new rival vehicles, they chose the gasoline-powered car over the clean, cheap and compact safety bicycle. Then in 1903, the first reinforced concrete skyscraper went up in Cincinnati, Ohio.

Concrete helps answer the vexed question of why modern cities are ugly. Before the 20th century, local, low-carbon, organic building materials, such as Parisian limestone, helped houses blend with the landscape. And before developers acquired the technology to build high, buildings were on a human scale, small enough for a pedestrian to take in: think of Haussmann’s six storeys, often with fine individual details. But the 20th century brought concrete and glass towers with undifferentiated flat surfaces. A woman I know who grew up in an English new town says she realised only later that living amid ugliness had made her childhood unhappier.