Cheonggyecheon (淸溪川), meaning ‘crystal clear stream’ in Chinese, runs east to west through the historic centre of Seoul. It represents a dramatic economic, social and environmental urban transformation of Seoul. With Seoul’s modernization in the 1950s, the stream served as a sewage canal, lined with squatter housing and illegal industrial businesses. Subsequently, the stream was covered and converted into an arterial road. In the early 1970s, an elevated highway was constructed to accommodate heavy traffic. By the 1980s, however, the congestion and pollution of the Cheonggyecheon area epitomized the worst aspects of uncontrolled urbanization. The dismantling of the highway and restoration of the Cheonggyecheon waterway in the 2000s created an urban amenity that resulted in an unprecedented regeneration of Seoul. The Cheonggyecheon Restoration Project represents a paradigm shift in metropolitan urban planning and urban governance. It provides a template for green urban regeneration. It contributes to the correction of the economic imbalance between the northern and the southern parts of Seoul. However, the resulting gentrification and the destruction of social networks due to forced relocation of existing trades and industries are the cost of this restoration initiative.