Longyandong is located in Dongguayuan, a branch of Yuechengling, 5 kilometers away from Quanzhou County and only 3 kilometers away from National Highway 322. It is one of the eight ancient sights. Longyandong, also known as longyan temple, was built in the rock mouth in the Song Dynasty with Purun Temple. There is a round boulder in the cave, which is immersed in the middle stream and washed by the spring water, making a loud noise, and the rock wall echoes like the sound of a dragon mill, hence the name Longyan. During the period of War of Resistance against Japanese Aggression, Du Kuan, commander of the Fifth Army of the National Revolutionary Army, widened and filled caves and built an arsenal. 1969, the General Logistics Department of the People's Liberation Army of China built a hospital here, and then dug caves, which expanded into the largest underground hospital in China and the only cave hospital in the whole army. There are five-story buildings (six floors in some areas), auditoriums, restaurants, squares and power stations in the cave, with a total construction area of10.3 million square meters, fully air-conditioned. Wu Xiuquan and Hong Xuezhi visited the cave successively.

The back hole is shaped like a bell mouth, like a dragon opening its mouth and shouting. The hole is inclined to the sky, about 40 meters high and 30 meters wide. The cliff is covered with stone emulsion, stone curtain and waterfall flying curtain. The waves are rough and the pearls are dripping, which is spectacular. After the cave, the ancient trees are towering, the virgin forest is lush, and a mountain is towering and unique, which makes this mountain look particularly solemn and simple. The canyon is about 1000 meters long, and the springs are gurgling, elegant and fresh, just like a paradise.