Geumjeongsanseong is the largest mountain fortress in the Republic of Korea today. It is located on Geumjeongsan in the Busan Metropolitan City.
Following the Japanese invasion of 1592 and the Manchu invasions of 1627 and of 1637, awareness of the necessity of national defence was heightened, especially against attacks from the sea. As a result of this awareness, this fortress was built in the 29th year of the reign of King Sukjong. The inner and the outer walls were mainly built of natural stones, but weak portions were reinforced with artificially worked square stone blocks. The walls are about 17 kilometers in length and from 1.5 meters to 3 meters in height. The area surrounded by the fortress is about 8.2 square kilometers.
Wikipedia https://en.wikipedia.org/wiki/Geumjeongsanseong
Address South Korea
Coordinates 35°16'58.447" N 129°3'17.899" E