Achasan, Mountain summit in Gwangjin District, South Korea

Achasan is a granite hill of 287 m on the Seoul–Guri boundary, its summit, Yongsanbong, reached by trails from Gwangnaru and Yongmasan stations. The slope holds the stone walls of Achasan Fortress (Sageok 234), a Baekje construction facing the Han River, plus a rock cave where Uisang practiced and a 3 m stone ball linked to the Ondal legend.

The mountain contains fortress remains from the Three Kingdoms Period, demonstrating its strategic importance as a defensive position along the Han River. These ancient structures have shaped its landscape for centuries.

The Goguryeojeong Pavilion serves as a gathering point where visitors observe traditional Korean architectural styles while viewing Seoul's modern skyline. Here, old building forms blend naturally with views of the contemporary city.

You can access the hiking trails from Gwangnaru Station on Line 5, with different routes taking between one and a half to two and a half hours to complete. Choose your path based on your fitness level and available time.

Achasan Fortress, a Baekje-era stone rampart, faces the Han River and looks across to Pungnaptoseong, the earthen fort many scholars identify as the Baekje capital. From the fort the river is visible almost in its entirety as it flows through Seoul, the closest vantage point for viewing the Han from above.