Busosanseong, Mountain fortress in Buyeo, South Korea

Busosanseong is a mountain fortress built from stone and mud on Mount Buso in Buyeo. The site features several pavilions including Baekhwajeong, Sajaru, Banwollu, and Yeongillu, which offer views of the surrounding landscape, along with defensive walls and gates.

The fortress was built in 538 CE during the Baekje Kingdom era and served as a strategic military post to protect Sabi, the kingdom's capital. It was an important defense structure during a period of political tension.

The name Busosanseong comes from Mount Buso, used since Unified Silla; earlier records in the Samguk Sagi call it Sabi-seong or Soburi-seong. Some scholars link "Busos" to "Buyeo", the name Baekje adopted for its state as Nambuyeo. Within the walls stand the Gun changteo warehouse site, the Nakhwaam rock where King Uija's court ladies are said to have leapt, and Goransa temple.

The site is relatively accessible for exploration, with various paths connecting the scattered pavilions and walls. Comfortable shoes are recommended since the location sits on a mountain with some steep sections to navigate.

The site is closely tied to the tragic end of the Baekje Kingdom, particularly through the story of Nakhwaam Rock. This location marks a pivotal moment when the kingdom fell to invading forces.