In Lanzhou, in the northwest, there is also a name called the city of watermills. The waterwheel in Lanzhou originated from the Ming Dynasty more than 400 years ago. It was still very popular until 50 or 60 years ago. The waterwheel turning on the bank of the Yellow River became a symbol of the city. The Yellow River traverses Lanzhou City. This city is also a city built along the river. The terrain of Lanzhou is both mountains on both sides. It can only develop in the east-west direction. The side is also the most scenic area, there are many attractions along the Yellow River. Zhongshan Bridge is the most famous bridge in Lanzhou. It has a history of more than 100 years. This iron bridge spans the Yellow River, with a bustling urban area on one side and Baita Mountain on the other, along the Yellow River. To the east, there is a waterwheel expo park. Speaking of Lanzhou's waterwheel, one person is mentioned. This person is called Duan Xuan, Lanzhou Duanjiatan, an official of the Ming Dynasty. Later, when he resigned and went home, he invented the Lanzhou waterwheel. He was welcomed by the local people and fought to build. He finally achieved the reputation of Lanzhou Waterwheel City. The segment has served as the royal history of Yunnan Road, and has a strong interest in the local car, so he sent people to paint and keep them. When I resigned and went home, I studied the waterwheel according to the pattern and the actual situation in Lanzhou, and finally succeeded in Jiajing thirty-five years (AD 1556). Before the invention of the waterwheel, the people of Lanzhou basically relied on the sky.