Haemieupseong is a large Joseon fortress town, completed in the late 15th century and still easy to read on foot. The walls, gates, and open interior give the place a calm, spacious feel, especially compared with busier palace sites.
The history is not only architectural. The fortress is also tied to Catholic martyrdom in the 19th century, which gives it a heavier layer than a simple military relic. It is one of Seosan's most straightforward sights for travelers without specialist knowledge of Korean history.