A fortress in the Geumgang River area, Gongsanseong is one of the earliest walls made to protect Gongju, the capital of the Baekje Dynasty. It was originally earthen walls but rebuilt with stones in the Joseon Dynasty. The exact date of its construction is unknown. What is known is that it was called Ungjinseong Fortress during the Baekje Dynasty, Gongjusanseong Fortress or Gongsanseong Fortress during the Goryeo Dynasty, and finally Ssangsusanseong Fortress since the Joseon Dynasty. There were four gates in the fortress, but only two of them remained before 1993: Jinnamnu Pavilion in the south and Gongbungnu Pavilion in the north. In 1993, the other two gates, Yeongdongnu Pavilion in the east and Geumseoru Pavilion in the west were restored. Other remains include -- in addition to a number of military facilities -- Ssangsujeong Pavilion, Yeongeunsa Temple, Yeonji Pond, Imnyugak Pavilion site, and Manharu Pavilion site. Many pieces of Baekje tiles including the lotus-patterned one, earthenware, and other relics from the Goryeo and Joseon Dynasty were also found. This is the place where King Uija stayed for a short time after the fall of the Baekje Dynasty and where the Baekje Restoration Movement got its power. It is also where the rebellion by Kim Heon-chang (822) took place in the Unified Silla Dynasty and where King Injo of the Joseon Dynasty took refuge following the revolt by Yi Gwal (1623). It had been the capital of Baekje Dynasty until King Seong moved it to Buyeo in 538; since then, it has continued to be treated as an administrative hub of the region.