Yongtai Ancient City, now located in Sitan Township, Jingtai County, Gansu Province, was built in the 36th year of Ming Wanli (1608). It has a history of more than 400 years and was built by the Ming government to defend against the invasion of minorities in the north. Upon completion, it will become a military fortress, and Lanzhou will be stationed in this castle. At that time, there were more than 2,000 soldiers in the city and 500 horsemen. There were gunpowder fields, forage yards, mills, and horse farms. Yongtai City Wall is made of loess, with a circumference of 1717 meters, a wall height of 12 meters, a city base of 6 meters and an area of 318 acres. The entire city plane is elliptical, the city gate opens to the south, the outer gate is built, the outer door is called "Yongning Gate", the inner door is called "Yongtai Gate", and the door is slightly westward, resembling a glans. It is built on the four sides and is shaped like a tortoise. There are five beacon towers in the north of the city that are gradually going away, resembling a turtle tail. There is a moat in the city, about 6 meters wide and about 1 to 2.5 meters deep. The shape of the entire city resembles a tortoise, hence the name "Kurch City."