Ruins of an enormous mountain fortress, built in 470 – 473 AD. Measured length of the walls is 1,680 – 1880 m and they were 13 – 20 m tall.

Location, GPS coordinates:	36.4885 N 127.7423 E
Categories:	Fortresses and forts
Values:	Architecture, Visual
Rating:
Where is located?	Asia, South Korea, North Chungcheong, to the east from Boeun, Eoam-ri

Samnyeon sanseong on the map