The vast majority of historic sites in Korea are forts and fortresses. No one knows exactly when they were built, however, the Pungnaptoseong fortress (풍납토성) was built during the Baekje Dynasty and Bukhansanseong fortress (북한산성) is estimated to have been built around 132 A.D. Hwaseong Haenggung (화성행궁), located in Suwon (수원) just outside of Seoul, has been named Historic Sites No.3 by the Korean government. Impressively, the fortress was completed in only two years, in 1796. The walls of the fortress are 5.7 kilometers in circumference and contain over 50 structures.