Cheonggyecheon
Cheonggyecheon (Korean: 청계천, Korean pronunciation: [t͡ɕʰʌŋ.ɡje.t͡ɕʰʌn]) is a 10.9-kilometre-long (6.8 mi) stream and public space in downtown Seoul, South Korea. A natural stream sourced from the Suseongdong Valley in Inwangsan, it was historically maintained as part of Seoul's early sewerage until the mid-20th century, when post-Korean War rapid economic development and deteriorating conditions prompted the filling of the stream with concrete and the construction of an elevated freeway, the Cheonggye Expressway, in its place.