Built with rammed earth inside and brick and stone outside, the ancient city walls measure 10 meters high and 6162.7 meters long with 3-5 meters wide tops. Except the southern wall, which zigzags a bit according to the land contour, the other three walls all go straight, making the city area a square one. One city gate was built each to the southern to northern walls and two city gates were built each to the western and eastern walls. All six city gates have gate towers and inside gates attached to them. A watch tower was built on the wall top every 50-100 meters away, totaling 72 watchtowers in all along the four walls. The parapets measuring 2 meters high each were built along the outside edges of the walls with 3000 mouths left open for defense shooting. It is said that Confucius once had 72 disciples and 3000 students, therefore 72 watch towers and 3000 parapets’ openings on the top of the four walls were built. There were another four grand watch towers originally built on the four corners of the squared walls, but they all disappeared long ago, with only one Great Scholar Tower and one Nameroll Calling Platform on the wall tops left today. Dug around the walls is a defense ditch measuring more than 3.3 meters in depth and 3.3 meters in width with trees planted along it. A drawbridge is built in front of each gate.
Pingyao City is called "Tortoise City" by local people, because the southern gate and the northern gate look like the head and tail of a tortoise, respectively, while the two gates in the eastern wall and two gates in the western wall look much like the four legs of a tortoise. With the outer gate extended a bit out of the inner southern gate and two wells dug outside on either side, the tortoise city seems, to have its own head and its two eyes. What's more, the northern gate curves a bit towards the east, the four gates in both the western and eastern walls curve a bit all towards the south. This design shows as if a tortoise is crawling forward. Some people say it was for preventing the flood coming from the north-west that the city walls were built in such a pattern. But there is no definite proof for this saying except the symbolic meaning of eternity given by the shape of a tortoise according to the Chinese mentality.