Hanyangdoseong (Seoul City Wall) is a fortress built to mark the boundaries of Hanseongbu, the capital of the Joseon Dynasty, to assert its authority, and to defend against external invasions. Constructed in the 5th year of King Taejo's reign (1396) along the ridgelines of the four inner mountains (內四山) — Baegak (Bugaksan), Nakta (Naksan), Mongmyeok (Namsan), and Inwang — it has been rebuilt multiple times since. With an average height of approximately 5~8m and a total length of approximately 18.6km, Hanyangdoseong served as a functioning city wall for the longest period (1396~1910, 514 years) of any existing city wall in the world. Hanyangdoseong had four great gates and four small gates. The four great gates are Heunginjimun, Donuimun, Sungnyemun, and Sukjeongmun, and the four small gates are Hyehwamun, Soeuimun, Gwanghuimun, and Changuimun. Of these, Donuimun and Soeuimun have been lost. In addition, Ogansu Gate and Igansu Gate were placed near Heunginjimun to connect waterways outside the city wall.

Hanyangdoseong can be explored in a single day by following the Sunseong-gil trail, but it is recommended to divide the walk into 6 sections centered on the four inner mountains: the Baegak, Naksan, Namsan (Mongmyeoksan), and Inwangsan sections, as well as the Heunginjimun and Sungnyemun sections where the city wall has been lost.

Website : https://seoulcitywall.seoul.go.kr/wallcourse.do

Source

http://www.junggu.seoul.kr/tour/