Longtan Mountain Fortress (龙潭山城)

Longtan Mountain Fortress is a Goguryeo-era hill fortress on Longtan Mountain in Longtan District of Jilin City, in Jilin province, overlooking the Songhua River. It is generally dated to the 4th to 5th centuries AD, when Goguryeo extended its authority north from the Yalu valley across the Songhua basin, and it is regarded by archaeologists as an outlying defensive and administrative centre of that kingdom. The fortress was built on the ridge of the mountain and encloses a compact area with natural slopes forming part of the defences. Sections of rammed-earth and stone wall survive along the crest, together with the foundations of gates, platforms that may have supported lookout structures, and storage pits. A notable feature is the Dragon Pool, a spring-fed well within the fortress that has long been associated with local legend and which supplied the garrison with water. A smaller Tiger Pool lies nearby in the same hillside park. Excavations have yielded Goguryeo pottery, iron tools and weapons, and roof tiles, as well as later items from the Bohai and Jin periods, showing that the hill continued to be used for centuries. The site lies within a public park and is one of the better opportunities to see Goguryeo defensive works outside Ji'an. A signed trail leads from the park gate through the wall remains to the pool and to the park's temple and lookout, with views across Jilin City. The fortress has been protected as a provincial cultural relic. Preservation is modest, with wall sections stabilised and marked by interpretive boards. A visit takes about 1.5 hours, and the climb is moderate on paved and dirt paths.