Achasan Mountain

Achasan is a low granite mountain on the border between Gwangjin District in Seoul and the city of Guri. Its height is given as anywhere from 285 to 296 m depending on the source, but from the ridge you look out over the Han River and the eastern half of Seoul. Fortress walls and Goguryeo outposts from the era when the Three Kingdoms fought over the Han basin turn a short hike into a history lesson, and you can start right from a subway station.

A mountain the Three Kingdoms fought over

Achasan was designated a nature park in 1973. On its southern slope, Achasanseong Fortress (Historic Site) is a Three Kingdoms-era mountain fortress with walls 1,125 m in circumference and around 10 m high on average, facing Pungnaptoseong across the river. Two sad stories are told here. When the Baekje capital Hanseong fell to Goguryeo, King Gaero of Baekje was killed below these walls; and General Ondal, son-in-law of the Goguryeo king Pyeongwon, died beneath the fortress fighting Silla to win back lost land. A spring inside the walls is called "Ondal's spring". Who first built the fortress is still debated, but excavations have mostly turned up Goguryeo-style pottery.

Scattered along the ridges, the Fortresses in Achasan (Historic Site) are a group of about 17 small outposts on Achasan, Yongmasan and Mangusan. Around ten of them are thought to be Goguryeo forts, the densest concentration of Goguryeo remains in South Korea. They are regarded as key evidence for the period from Goguryeo's conquest of the Han basin in the late 5th century to its loss to Silla and Baekje in 551.

What to see

• Han River views: from the fortress area you can follow almost the entire course of the Han through Seoul. The halfway viewpoint and the summit open up views upstream towards Guri and Hanam.
• Goguryeojeong Pavilion: an octagonal pavilion halfway up, a good rest stop with a view over the city.
• Yongmasan: the highest peak of the Achasan range at 348 m. Many hikers walk the ridge from Achasan to Yongmasan.
• Achasan Ecological Park: a garden of native plants just above the car park at the trailhead, good for a short wander before or after the climb.
• Three-storey stone pagoda of Achasan, Guri: a pagoda standing on a rock on the Guri side, a Gyeonggi provincial cultural heritage.
• Old stories: many tales about Hong Gye-gwan, a famous fortune-teller of the 16th century, are tied to the mountain. Until the 1950s it was a celebrated riverside beauty spot, and President Syngman Rhee had a villa here.

Tripto tips

• Routes: from the Mannam Plaza trailhead via the pavilion, the summit and Yongma Peak takes about 2.5 hours; summit and down to Gingorang Sports Park on the Yongmasan side about 1 hour 50 minutes. The trails are well maintained and fine for beginners.
• Getting there: from Achasan or Gwangnaru stations on Line 5, take village bus Gwangjin 03 to the trailhead. You can also walk up from Yongmasan Station on Line 7.
• Admission: free and open at all hours.
• When to go: autumn foliage season is especially popular. The views towards the Han are lovely late in the day, but leave enough time to get down before dark.
• Preparation: some sections cross bare granite, so wear shoes with good grip and carry water.