Achasanseong

Achasanseong Fortress, an earthen mountain fortress located on Achasan Mountain in Seoul, South Korea, dates back to the Korean Three Kingdoms period. Initially constructed by the Baekje kingdom, it served as a strategic defensive structure against potential invasions from the north, particularly from Goguryeo. This fortress, with a perimeter of approximately 1 kilometer and an area of 3375 square meters, played a crucial role in safeguarding the Baekje capital, Hansŏng. Historical records from the Samguk Sagi highlight its fortification by King Chaekgye of Baekje. By 475 CE, the fortress fell to Goguryeo, leading to the execution of King Gaero. It was later captured by Silla in 553 CE. Achasanseong stands as a testimony to the region's turbulent history and serves as a significant archaeological and cultural site.