Horogoru Fortress

Above a basalt cliff on the Imjingang River rises a tall, grass-covered embankment. It looks like a hill, but it is a Three Kingdoms-era wall. Horogoru is a triangular fortress that uses the river and its cliffs as ready-made defences, a relic of the time when the Imjingang served as a frontier between Goguryeo and its rivals to the south. In late summer the field in front turns into a sea of sunflowers, and many people come for the sunset.

A fortress built on cliffs

Horogoru stands on a triangular plateau where a tributary meets the Imjingang, which flows from northeast to southwest. On two sides, vertical basalt cliffs along the water act as natural walls; only the open east side was closed with a high rampart. Archaeologists call this type a riverside flatland fortress, and together with nearby Dangposeong and Eundae-riseong it is a form found only along the Imjingang and Hantangang.

The circuit of the walls is about 400 m: the south wall measures 161.9 m, the north wall 146 m, and the surviving east wall 93 m. The interior lies around 22 m above sea level, the top of the wall about 30 m. Command posts stood on the highest point of the east wall and at the western tip, and the only gate is thought to have been at the southern end of the east wall.

Why build a fortress here?

Horo means gourd. The Imjingang bends like a gourd around here, and the ford was called Horotan and the river Horoha, which is probably where the fortress got its name. Outside the monsoon season the water at Horotan was only knee-deep, so people could cross on foot or on horseback, and the shortest land route from Kaesong to Seoul passed this way. There was no better place to guard the crossing.

Horogoru was built by Goguryeo between the 5th and 7th centuries to hold off Baekje and Silla, and it seems to have been a key stronghold on Goguryeo's southern frontier. The east wall, the only side not facing the river, has a core of packed clay and decomposed granite faced with stone inside and out, a technique also seen at Goguryeo sites such as Gungnae Fortress in Ji'an and Daeseongsan Fortress in Pyongyang. When Silla later took the fortress, it did not demolish the old walls but repaired them by adding new stonework on the outside.

Records and excavations

The first record identifying Horogoru as a Three Kingdoms site appears in the Dongguk Yeojido, compiled in 1656. A colonial-era survey report of 1919 published plans and photographs, and full-scale research and excavation followed between 1991 and 2003. Finds include Goguryeo weights, a three-legged inkstone, arrowheads, pottery and a gilt-bronze Buddha, while storage pits held carbonised rice, soybeans and millet along with bones of cattle, horses, deer, dogs and wild boar, a glimpse of daily life in the garrison. During the Korean War, gun emplacements damaged the top of the walls. It was designated a Historic Site on 2 January 2006.

What to see

• The east wall: the huge grassy mound is the east wall. Wooden stairs lead to the top, where the flat interior and the course of the Imjingang open up below you.
• The river cliffs: look down from the edge of the fortress to see how sheer the basalt cliffs that replaced a wall really are.
• Wall section and information hall: part of the east wall has been cut open to show how it was built, and Yeoncheon County has added an information hall, an observation deck and a memorial platform facing the river.
• Sunflower field: sunflowers are planted in the field in front of the fortress and peak around September, when the "Tongil Sunflower Festival" is held each year (in 2026 it opened on 3 September).

Tripto tips

• When to go: early to mid September for the sunflowers, and late afternoon for the light; from the top of the wall you can watch the sun set over the river.
• Time needed: 30 minutes to 1 hour to climb the east wall and walk around the interior.
• What to bring: the grassy site has almost no shade, so take a hat and water in summer. The slopes of the wall are slippery; use the stairs.
• Getting there: public transport is impractical, so driving is the realistic option. Combine it with nearby Dangposeong, a similar Goguryeo fortress on the same river.