Introduction to Ninghai City: Ninghai City is located to the north of Shicheng into the sea. Ninghai City is an important part of the Shanhaiguan Laolongtou military defense system. It is the most complete and largest existing Ming Dynasty military camp in my country. The total length of the trapezoid is 899 meters. On the right is the "General Administration" and on the left is the "Longwuying" room. There are also merit temples for worshiping pioneer generals, as well as the Dragon King Temple and Guandi Temple for the protection of gods.