On a crisp December morning, office workers and tourists stroll along a tree-lined stream in central Seoul, pausing on stepping stones that cross its flowing waters. It’s difficult to imagine that just over 20 years ago, this was a vast elevated highway carrying 168,000 cars daily through the heart of South Korea’s capital.

Cheonggyecheon, a stream that runs for about 3.5 miles (nearly 6km) through Seoul, was one of the earliest experiments in an increasing trend in cities globally: turning spaces where there was once car or rail infrastructure into spaces for pedestrians and cyclists. It’s a powerful example of the way that these spaces can become loved and popular, along with projects such as the High Line in New York, where an old railway track has been turned into a raised park, or the city moat in Utrecht, where a multi-lane road (nicknamed the “motorway from nothing to nowhere”) was converted back into a canal, in part of a huge continuing push to allow pedestrians and cyclists to dominate the city’s centre.

Plenty of regrets have followed the 20th-century rush to build infrastructure for cars, and some of the monstrosities that have resulted. Planners on every continent now look hard at the ways in which people can be put back at the centre of our cities.

In Seoul, the restored waterway has been a triumph. It doesn’t just provide a peaceful refuge from the city’s busy streets, it serves as a cultural corridor with year-round festivals and performances, while helping cool the surrounding neighbourhoods, fighting air pollution and managing increasingly intense monsoon floods.

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