Linhai Ancient Great Wall was first built in Jin Dynasty and completed in Tang Dynasty. It is supported by Longgu in the north and Jinzi in the south. The Lingjiang River converges with the water of Yong'an and Shifeng and flows around the city. The city is built on the mountain, the mountain is beside the water, and the water embraces the city. The mountain, water and city are integrated and unique. The northern part is the most steep, relying on the mountain, winding and winding, like a dragon dancing, known as "Jiangnan Badaling". Two mountains stand side by side, two waters depend on each other, and a group of cities and towers constitute the unique style of the ancient city. In addition to being used for defense, the ancient city also has flood control. The four city gates and the urn city are unique in structure. The city has beautiful scenery, beautiful environment, many historical sites, profound cultural heritage, and rich cultural and natural landscapes. It is also called "Jiangnan Ancient Great Wall". The reason for its construction is to fight against Japanese pirates. There is a square city platform every 100 meters. In the middle of the Great Wall, there is also a "Watching the Sky Platform". Linhai Ancient City Wall has a long history. Since its creation in the Jin Dynasty, it has been more than 1,600 years. It has been continuously built and expanded in the Tang, Song, Yuan, Ming and Qing dynasties, and its main part has been preserved to this day. The ancient city wall was built along the river, following the terrain of the mountain, winding and twisting, majestic and spectacular. Especially the section of Beigushan, built on the top of a dangerous cliff, flying and circling, with enemy towers standing in rows, battlements connected to the clouds, and towers standing high. Compared with Badaling in Beijing, it can be called a double wonder. It is not an exaggeration to call it "Jiangnan Badaling". What's more unique is that on both sides of the Linhai ancient city wall, there are towering ancient trees that are green all year round. The city wall is hidden in the green bushes, adding a bit of elegance. In addition to the function of defending against enemies, the Linhai ancient city wall also has a very important function, which is flood prevention. One third of the length of the intangible cultural heritage Linhai Ancient City Wall was built along the Lingjiang River. Taizhou Prefecture City is located near the Lingjiang River entering the sea. When the river water meets the tide, the water level rises and often floods the city. The city wall is like a levee, resisting the impact of floods for more than a thousand years. For this reason, the Linhai City Wall took unique measures in its construction and design, building the city wall into an arc shape, especially the "horse face" facing the water into a semicircular arc shape (the other side is still square), which is very rare among the ancient city walls in the country, and it is still a solitary case as far as we know. Due to the flood-fighting function of the city wall, when the Yuan Dynasty destroyed the Southern Song Dynasty, the Yuan Emperor ordered the demolition of all the ancient city walls in Jiangnan to facilitate the iron cavalry to drive straight in, but the Linhai City Wall was specially exempted from demolition due to its irreplaceable flood-fighting function. It is more worth mentioning that the Linhai Ancient City, known as the "Badaling of Jiangnan", made a huge contribution to the anti-Japanese struggle in the Ming Dynasty. Qi Jiguang, a famous general who fought against Japanese pirates, spent eight years in Linhai. Together with Tan Lun, the prefect of Taizhou, he transformed the structure of the ancient city wall of Linhai, heightened and thickened it, and creatively built thirteen two-story hollow enemy towers, greatly enhancing the defense capability. The Qi family army used the ancient city of Linhai as a base to support the coastal defense of Fujian and Zhejiang, repeatedly defeated the Japanese pirates nine times and won nine victories, washed away the national humiliation, raised their heads and greatly boosted the national prestige. Later, due to the need for the defense of the Great Wall in the north, the court specially transferred Qi Jiguang and Tan Lun to Beijing and entrusted them with important tasks. When Qi Jiguang was the general of Jizhen, he applied his experience in building city defense in Linhai to the expansion and strengthening of the Great Wall in the north. The Great Walls in Jizhen, Changzhen, Xuanfu, Datong, Shanxi and other towns that exist today have been improved, expanded and strengthened according to his planning and design. In order to meet his needs for rebuilding the Great Wall in the north, he specially transferred 3,000 "Jiangdong soldiers" who had participated in the reconstruction of the Linhai city wall to serve as foremen, supervisors and technical guides. The majestic appearance of the Great Wall at Badaling, Mutianyu, Simatai, Gubeikou, Huangyaguan in Tianjin, Laolongtou near Shanhaiguan in Hebei, Jiaoshan, etc., are all left after Qi Jiguang's improvement. It can be said that the Linhai Ancient City Wall is the "model" and "blueprint" of the Great Wall at Badaling and other places in Beijing.