Among them is the Ryonggolsan Castle representative of the Middle Ages.

The castle, located in Pangok-ri of Yomju County, was built in the period of Koguryo Kingdom (B.C. 277-A.D. 668) and rebuilt in 1692.

The circumferences of its inner and outer walls are 670 and 2,500 meters each.

According to an archive, the castle consisted of 66 bastions, 316 battlements, 7 gun batteries and 1 obstacle.

Its gate was made between rocks in consideration of transport and defence conditions.

Remained in the inner walls are such building sites as armory, granary and barracks.

The Ryonggolsan Castle associated with the history of the Korean people's struggle against foreign invaders has been preserved well as a national cultural heritage.