It's not a river. It's just a little stream, some 6 km long, running through downtown Seoul and emptying into the Han River.
Most people would normally call it a canal. But, at this moment, it's the most famous waterway in South Korea and few urban waterways anywhere come close to it as a symbol of civic pride.
To millions of Koreans, it lies at the heart of Seoul's effort to transform itself into an eco-friendly city.
The stream has a name, Cheongyye (literally meaning "clean valley water"), and a chequered history. It used to be a key waterway, crossed by no fewer than 22 bridges, when Seoul was a small settlement.
But as refugees poured into the place in the wake of the Korean War, slums grew along its banks, and in no time sewage and all kinds of waste began to fill it up.
The stream became so contaminated that in 1958 the government decided to cover it up. In 1968, an elevated highway was built above it to deal with the city's growing, and worsening, traffic.
Then something happened. Seoul's mayor, Lee Myung Bak, when he was still head of Hyundai Engineering and Construction, chanced one day to get inside the stream's covered passage.
There, in a shaft of sunlight streaking through a chink in the tunnel's roof, he saw a wild flower blooming, helpless in the surrounding darkness.
"It brought tears to my eyes," he later said. It also brought ideas to his mind. He decided to quit Hyundai and run for mayor, and by the time he won the election in 2002, restoring the Cheonggye to its former glory had become for him an article of civic faith.
He had the elevated highway torn down and the stream's concrete covers removed, and launched a $330 million, two-year project to reinstate the Cheonggye as a major downtown attraction.
The stream has been thoroughly dredged, its walls have been paved, with tiles in some stretches that citizens themselves have paid for, and all its 22 former bridges have been rebuilt.
Along both sides of the Cheonggye, walks and promenades have been built, lined with trees and flowering plants. Last May 31, tens of thousands of tonnes of water, drawn from the Han River, was poured into the stream to rejuvenate its flow and flush out its pollution.
By the time the stream is formally opened on October 1, there will be fountains, waterfalls, forested arenas, artificial ponds, and, of course, resting places along its entire stretch.
The Cheonggye project is the latest example of how some Asian cities are trying to use their waterways as agents of urban transformation.
Those who know what the Singapore River used to be in earlier days would be amazed to see what it has become now.
Its stink and filth have totally disappeared and its waters have turned clean and fresh. From a stretch of crumbling old godowns and shophouses that people generally avoided, it has come to be the favoured haunt of locals and tourists alike, bustling during the day, scintillating at night, a visual feast of dazzling colours and lights, and a huge, fairy-tale complex of fine dining, shopping and entertainment.
It's been a lesson that others are trying to emulate and is clearly behind Shanghai's ongoing effort to clean up the Suzhou Creek.
The creek, about 125 km long, rising from the Taihu lake in Jianshu province, crosses Shanghai east to west before emptying into the Huangpu River, and it's mainly this city stretch, some 24 km long, turned into a black and stinking sewer from years of dumping of untreated municipal and industrial wastes, that the authorities will be spending almost $1.5 billion to restore a project that began in 1999 and will end in 2010.
Besides cleaning up the creek and augmenting its flow, some 100 hectare of green will be developed along the waterfront.
A 13 km downtown section, from Zhongshan Park in the west to the Huangpu River in the east, is earmarked for setting up entertainment facilities, replacing dilapidated residential and industrial buildings.
The creek's northern bank, in the city's Zhabei district, will be rebuilt as a European-style, up-market entertainment and shopping area, which a group of French and German architects is designing.
All along the city part of the creek, yacht docks, inns, hotels, and outdoor bars are planned.
This is one part of the Asian picture. We also have, in the other Asia, cities like Bangkok with its klongs, Manila with its esteros, and Kolkata with its nullahs and khals, stinking urban waterways about which very little is being done.
Bangkok, to be fair, is at least using its klongs as an alternative means of transportation. Manila and Kolkata are letting their precious waterways simply choke out of existence.
Does that tell us anything?