Introduction to the castle complex in the Song Dynasty: In the 39th year of Jiajing in the Ming Dynasty (1560), a city wall was built to keep out Japanese pirates, and it was called Liancunbao. The plane of the fort is slightly oval, with a circumference of 1258 meters (currently 850 meters). The wall is built with cobblestones and rammed earth in the middle. The wall base is 4 meters thick.