Yongtai Fortress built
1608 CE.
Shown on the map at 37.136°, 103.846°.
Yongtai Fortress is a village and historical fortress town in Sitan Township, Jingtai County, Baiyin City, Gansu, China. Built in 1608 by the Ming dynasty rulers to defend against attacks from northern minorities, it stationed 2000 infantrymen and 500 cavalry units. The entire fort is enclosed by a rammed earth wall including defensive towers. Due to desertification, the village is now mostly abandoned, dropping from 1500 people in the 1950s, to around 100 today.
Text from the Wikipedia article Yongtai Fortress, licensed CC BY-SA 4.0.