Mount Achasan is 295.7 meters high, stretching from Seoul to Guri, and is a very popular hiking spot for locals and tourists alike. It takes about 40 minutes to climb to the summit, which offers a stunning panoramic view of the Han River, Seoul and the surrounding areas. Twenty forts have been discovered along the mountain, and their origin has been estimated to the Three Kingdoms era. Research indicated that some of the ruins were in fact part of a military fortress built during the Goguryeo era. In light of these findings, the mountain was officially designated as a historical site in 2004. .