What is the origin of Longtan Mountain in Jilin?

Longtan Mountain stands on the right bank of Songhua River in the northeast of Jilin City, with steep mountains and steep rivers. Koguryo Mountain City site on the mountain is a grand project of ancient northeast minority architecture in China. This used to be a military castle. Nantianmen, the main peak, is 388 meters above sea level. It used to be the platform of the ancient city, with a panoramic view of Jilin.

A group of temple buildings on the mountain are collectively called Longfeng Temple, including Longwang Temple, Kannonji Temple and Guandi Temple, which were built in the early Qing Dynasty. After Emperor Qianlong visited Changbai Mountain in Jilin in 1754, he specially visited Longtan Mountain and wrote a plaque for Fu You Dadong in Guanyin Hall. Longtan Mountain is named Longtan because there is a pool of water in the valley in the northwest corner of the mountain city. According to folklore, the green dragon in front of the Jade Emperor Temple was punished by the Jade Emperor for violating heaven. This dragon is vicious and persistent, and it often floods and harms the people. When the jade emperor knew about it, he flew into a rage. He sent heavenly soldiers to hold it down, chained it to the bottom of the pool, and tied the other end of the chain to the big tree by the pool. In the early years, a chain was tied to the trunk next to the water dungeon. When someone pulled the chain, dark clouds rolled, the wind blew and the pool expanded. In fact, the legendary Longsuo water dungeon is a large artificial water storage tank in the mountain city. The east, west, north and south of the pool wall are made of square granite, and the south is a natural stone wall. On the hillside not far from the dungeon, there is also a dry dungeon. The walls of the prison are granite, round and about 3 meters deep, and there is no water. According to textual research, it is said to be an ancient prison for holding criminals and a place for storing food. By then, with strong city walls and supporting projects such as water dungeons and dry dungeons, Koguryo soldiers guarding the mountain city may be able to sit back and relax.