Cheonggyecheon is an 8.4 km (5.2 miles) long, modern public recreation space in downtown Seoul, South Korea that was created after a massive urban renewal project to reopen a stream that, with the post-war economic development was covered by transportation infrastructure. The $900 million project initially attracted much public criticism but, after opening in 2005, has become popular among city residents andtourists.

The stream was opened to the public in September 2005 and was lauded as a major success in urban renewal and beautification. However, there was considerable opposition from the previous mayoral administration of Goh Kun, which feared gentrification of the adjacent areas that housed many shops and small businesses in the machine trades.

Creating the environment with clean water and natural habitats was the most significant achievement of the project. Species of fish, birds, and insects have increased significantly as a result of the stream excavation.[4] The stream helps to cool down the temperature on the nearby areas by 3.6 °C on average versus other parts of Seoul.[5] The number of vehicles entering downtown Seoul has shown a decrease of 2.3%, with an increasing number of users of buses (by 1.4%) and subways (by 4.3% - daily average of 430,000 people) as a result of the demolition of the two heavily-used roads.[6] This has a positive influence by improving the atmospheric environment in the region.

The project attempted to promote the urban economy through amplifying urban infrastructure for a competitive city within the existing business and industrial area centered on the stream. The Urban renewal project was the catalyst of revitalization in downtown Seoul. Cheonggyecheon became a centre for cultural and economic activities.