Underneath many large cities lie buried and lost rivers. Sometimes, they return to the surface world.
As metropolitan areas grow and sprawl, they run into rivers, streams, and creeks. Rather than build around all of these rivers or divert them, it has been common practice to build over them. The rivers go underground, becoming part of the sewer system or just trickling away in perpetual darkness.
The most famous of these is the River Fleet, a tributary of the River Thames in London. In medieval England it was an important river with a dock and a bridge. Boudica reputedly fought the Romans on that bridge; the character Fagin in Oliver Twist lived next to it. As London expanded its headwaters were dammed and it was polluted with the run-offs of the city around it. It’s mostly underground now, leaving a stamp on the city only in the form of names (Fleet Street) and shapes (the curve next to Kings Cross Station).
But not all such rivers stay hidden. Daylighting is the practice of resurrecting lost waterways. In Seoul, a stream called the Cheonggyecheon was buried under a highway from 1968 on. In 2003, as part of an urban restoration, the highway was removed and the Cheonggyecheon came back to day and light as a recreational space in the city’s CBD.
An interesting side note: traffic in Seoul improved after that highway was removed, illustrating the reverse side of the congestion paradox I wrote about back in August and giving hope to other lost rivers.
[Thanks to Siobhan L. for suggesting this topic]