Cheonggyecheon is a man-made stream filled with water originating in mountains surrounding the capital such as Mongmyeoksan, Inwangsan, Bugaksan, and Naksan. It runs through Seoul from west to east for 11km before joining Jungnangcheon Stream, which flows into Hangang River. There were many bridges over Cheonggyecheon such as Mojeongyo, Gwangtonggyo, Jangtonggyo, Supyogyo, Haranggyo, Hyogyeonggyo, Majeongyo, and Yeongdogyo as well as the Ogansumun Watergate Site. Changes in the structures were made in line with the changes in the capital. The remains of these bridges not only show the engineering technology of the Joseon Dynasty; their installation and changes are also valuable materials in the study of the expanding function of the capital and the system for capital management.
□ Gwangtonggyo Bridge Site
Gwangtonggyo was the biggest bridge in Seoul across the major north-south road from Gyeongbokgung Palace to Yukjo Street to Jongnu (bell tower) to Sungnyemun Gate, which formed the major thoroughfare through the city. Since the shops were located nearby, it was the bridge with the busiest traffic in Seoul. Apparently made when the capital was first constructed in the early Joseon period, it was initially an earthen bridge. The stone version was constructed in 1410 (10th year of Taejong), and the stones used are said to have come from Jeongneung, the Tomb of Queen Sindeok. The bridge was expanded in 1762 (38th year of Yeongjo).
□ Supyogyo Bridge Site
Supyogyo was first built in 1420 (2nd year of Sejong) under the name of Majeongyo. Since 1441 (23rd year of Sejong), however, it has been called Supyogyo when flat stones were placed beside the upstream part on the western side, and a water gauge (supyo) was installed there to measure the water level. Supyogyo, Seoul Tangible Cultural Heritage No. 18, has been reconstructed inside Jangchungdan Park. It is 27.6m long, 7.5m wide, and 3.4m high at its highest spot. The water gauge has been designated as Treasure No. 838.
□ Ogansumun Floodgate Site
Ogansumun was built over Cheonggycheon when the city of Seoul was reconstructed as a substructure of the city walls in the section between Dongdaemun Gate and Gwanghuimun Gate. The floodgate consisted of five arched gates, and its original appearance with the city walls above can be seen in a remaining photo.