Geumjeongsanseong Fortress (금정산성) is located on the peak of Mt. Geumjeongsan (801.5m) in Busan. Its original name was Dongrae Mountain Fortress, but it was changed because of its location.Its length is 17,377m, and 1.5m~3m high; it is the largest fortress in Korea. But now there is only a 4 km section remaining from the original. The exact time of the fortification is not recorded, but in reference to the location and size, it is presumed to have been built during the Three Kingdoms Era (when Goguryeo, Baekje, and Silla, the three dynasties, were fighting against each other). The present fortress was built in 1703, during the reign of Suk-Jong. It was built after Imjin Waeran (Japanese Invasion of Korea from 1592~1598) to prepare for any further invasions from Japan. It was first built with stones and was renovated in 1707. During the dark years under Japanese sovereignty it was damaged and devastated.In 1971, it was designated as private property. The West, East and South Gates have been reintegrated, and it is still undergoing the restoration process. On the fortress barbican there is Munru (watch tower). There is another watch tower called Mangru to watch for enemies. Different from other mountains, it is easy to find spring water here, and because it is a granite area, you can easily see rock caves and small and big rock peaks at Mt. Geumjeongsan.