Shanhaiguan, the first pass in the world, has four gates, which still exist today. The East Gate is the "first pass in the world" and the most complete preservation. Shanhaiguan, located at the eastern end of the Ming Great Wall, is the only place where the Ming Great Wall meets the sea. To the north is the western section of Liaoxi Corridor, which is the location of ancient Jieshi, so historians also call it "Jieshi Road". Shanhaiguan, named after Yanshan Mountain in the north and Bohai Sea in the south, is the dividing line between Hebei and Liao. Shanhaiguan city is about 4 kilometers in circumference, connected with the Great Wall and taking the city as the gateway. The city is 14 meters high and 7 meters thick, with four main doors and various defensive buildings. Shanhaiguan Ancient City is an important military defense system on the Great Wall of Wan Li in Ming Dynasty. The east building of Dongmen Town is magnificent. Because it is located in the pass, the situation is dangerous, and it is the first pass of the Great Wall of Wan Li to the east, so it is called "the first pass in the world" and is the landmark building of the ancient city of Shanhaiguan. On its left and right sides are Jingbian Building, Muying Building, Zhendong Building, Lulin Building and Weiyuan Hall. The five towers are lined up and evenly distributed on the 1000-meter-long Great Wall Line, which is called "East of Wuhu". There is a bell and drum tower in the center of the city, and the streets and alleys of Guancheng are in a chessboard layout, and four wengcheng guards outside the city, forming a trend of protecting the city; The outer layer includes Los Angeles, Yicheng, Acropolis and Shaocheng, which shows the architectural style of the ancient city of China with strict defense.