Cheonggyecheon: Seoul Tears Up a Highway to Bring Back a River

By the 1970s, Seoul had paved over the Cheonggyecheon stream and built an elevated expressway on top of it, burying the waterway under traffic and concrete. Between 2003 and 2005, the Seoul Metropolitan Government tore down the highway and restored 5.8 kilometers of open stream through the city center, pumping in water from the Han River and groundwater to keep it flowing. Within five years, the return of flowing water and greenery pushed overall biodiversity along the corridor up 639%, with fish species rising from 4 to 25 and bird species from 6 to 36, while nearby fine-particulate air pollution dropped by roughly a third. The restored stream now runs several degrees cooler than nearby streets and is cited internationally as a model for undoing car-centric urban infrastructure.