In Gaixia, now Haocheng, the world-famous Gaixia ancient battlefield site is left. The "Gaixia site" is a city built according to the terrain, with four arc-shaped corners. Exploration shows that the foundation of the city wall buried underground is relatively intact, the structure is relatively clear, and the direction is clear. Except for some sections of the west wall, the other four walls in the east, west, south and north are relatively straight. The lengths of the four walls in the east, west, south and north are approximately 410, 480, 280 and 340 meters respectively, with a total length of 1,510 meters. The area inside the city (excluding the city wall) is about 150,000 square meters, including the moat, and the area of the city site is nearly 200,000 square meters. Direction 350 degrees. The city is divided into four gates in the east, west, south and north. The original appearance of the four gates has not been preserved. The outline of the city wall is clearly visible from the outside, and it looks like a pot bottom from the inside. The highest point of the city wall has a drop of more than 3 meters from the farmland outside the city. The remains of the moat outside the city can be found. Although part of it has been leveled into farmland, most of it still exists.