Highlights the benefits of revitalizing the Cheonggyecheon Stream, a restoration project in Seoul, Korea, which has enhanced the urban environment, provided momentum to Seoul’s public transportation reform, and helped launch the broader regeneration of Seoul’s inner city areas. Unique and difficult challenges included an 18-lane elevated highway that stood over Cheonggyecheon Stream; the fast moving process, low cost, and the overlapping planning and construction phases also distinguish the Cheonggyecheon case from other studies. For large-scale undertakings such as the Cheonggyecheon restoration project, a long-term vision and a short-term action plan should develop simultaneously. The restoration’s first phase focused on more limited objectives, including the riverbed and the publicly owned area; in the later phases, Cheonggyecheon provided a green, public, and ecologically friendly space, which in turn helped drive the regeneration of the broader downtown area. This new space hosts pedestrian and cultural activities, provides habitats for animals and plants, and benefits the environment by lowering temperatures.