Yumen Pass and the Great Wall beacon tower ruins are located in the Gobi Desert 90 kilometers northwest of Dunhuang city. The attraction comprises three parts.

Yumen Pass (also known as xiao fang pan in Chinese) is the site of a military office in Yumen in the Western Han Dynasty. It is said that Khotan jade first entered the Central Plains (the area comprising the middle and lower reaches of the Yellow River) from this pass, hence its name. Now the parapets of the pass remain, in square rammed-earth structures.

The remaining city walls are 26.4 meters long south to north, 24 meters wide east to west, and 9.7 meters high. The upper part of the walls is 3.7 meters wide, the bottom is 4 to 4.9 meters wide, and the rammed section is 0.1 to 0.15 meters thick. With one gate on its east and north sides each, the pass covers a total area of 630 sq m. Around the pass are ruins of barracks, turrets and pagodas.

Hecang City (also known as da fang pan in Chinese) served as a munitions depot to store supplies for the western border lines in the Han Dynasty through to the Wei and Jin dynasties.

Situated 10 kilometers east of Yumen Pass, Hecang City was built on a natural earth station two meters above the river bed on the south bank of Shule River. In a rectangle layout, the south-facing rammed-earth structure has a south gate. Its walls extend 132 meters long east to west, 17 meters wide north to south, 6.7 meters high, and 1.5 meters thick.

Inside the city, there are three warehouses, separated by partition walls with two rows of ventilation windows on the top and bottom. Wing walls stand on the east, west and north sides of the city, with four piers in the corners. A beacon tower stands 100 meters south of the city and is called "Hecang Beacon Tower".