Imjonseong placed at the top of Bongsusan during Baekje Dynasty
Imjon Castle, located at the Bongsusan’s top in Daehung-myeon at the altitude of 483m, is a Temoi-styled stone hill-fort with about 2.4km circumference. Also called Daeheungsanseong, this castle seems to have been built by Baekje primarily to defend itself against the invasion from the north by Goguryeo.
The castle wall is about 250㎝ high and 350㎝ wide. The exterior of the southern wall is made up of stonework while the interior is of mixture of soil and stone. The southern wall has a water inlet covered with a wide slabstone, whose size is 70cm high and 30cm wide, which is connected to a gutter of 90cm depth and 60cm width dug to induce water into the castle. To make the castle as firm as possible, the castle’s four corners were constructed about 2m thicker and its height slightly higher than those of any other castle.
The southern gate with its thickly constructed vicinity is assumed to have been the main gate, leaving stone-structural parts of the gate on the left and right while the place assumed to be the northern gate remains as well. The inside of the castle has an almost flat slope, and Togipyeon(earthenware pieces), Giwapyeon(tile pieces) of Baekje and the terraced building site are unveiled inside the southern wall. Various documents record that this castle along with Geonji Sanseong (hill-fort) of Seocheon used to a base of Baekje’s Buhung-gun.