Guomari Castle (Litun) is located in Guomari Village, 7 kilometers north of Tongren County, on the terrace on the west bank of Longwu River, surrounded by mountains and rivers.

The castle was built in the Ming Dynasty. It was built to defend the border and defend against enemies. The castle is rectangular, 200 meters long from east to west and 180 meters long from north to south, covering an area of 36,000 square meters. The wall is rammed earth, with a base width of 4 meters, a remaining height of 10 meters, and a rammed layer of 13-15cm. There are three gates in the east, west and south. Each gate is a two-story building with a mani house.