In 2003, the city government began an urban renewal project to disassemble the expressway and restore the stream, which was completed in 2005 at a cost of over ₩386 billion (approximately US$281 million).

Cheonggyecheon is an 10.84 km (6.74 mi) stream flowing west to east through downtown Seoul,[2] and then meeting Jungnangcheon, which connects to the Han River and empties into the Yellow Sea.

The work, which included dredging and bolstering the banks of the stream and building bridges, was carried out every 2–3 years during this period from the reign of Taejong, the third king of Joseon.

[5][6] After the Korean War, more people migrated into Seoul to make their living and settled down along the stream in shabby makeshift houses.

The stream was covered up with concrete over 20 years starting in 1958, and a 5.6 km-long (3.5 mi), 16 m-wide (52 ft) elevated highway was completed in 1976.

[5] The Cheonggyecheon restoration project had the purpose of preserving the unique identity of the natural environment and the historic resources in the CBD of Seoul, and to reinforce the surrounding business area with information technology, international affairs and digital industries.

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.

[5] Some Korean environmental organizations have criticized its high costs and lack of ecological and historical authenticity, calling it purely symbolic and not truly beneficial to the city's eco-environment.