Introduction to the city wall: Pingyao City was built in accordance with the principle of "adapting measures to local conditions and using danger to control fortresses". It has a simple style, attaches great importance to defense, and is famous for its excellent craftsmanship and materials. The city is square in plan, and the city wall on the south side is built along the Zhongdu River, so it is slightly winding. The city wall is about 12 meters high, with an average width of 3.5 meters and a circumference of 6.4 kilometers. There is a moat outside the wall, with a width and depth of 4 meters. The inside of the wall is made of earth, the outside is wrapped with white ash, the top is paved with green bricks, and the inside is equipped with a horse path and an inward drainage channel. There are 6 gates and gate towers on the wall, a turret at each corner, and a watchtower every 50 meters. There are 72 gates in total, and a total of more than 3,000 crenellations. It is said that Confucius had three thousand disciples and seven sages. Designed by Twelve. However, except for the city gates and crenellations, most of the rest are in ruins. Among the six city gates, there is one in the north and south, and two in the east and west. There are attached urns outside the east and west gates, shaped like the head, tail and four legs of a turtle, and the layout of the streets in the city also resembles the patterns on the back of a turtle, so It is known as "Turtle City".