In the second year of Yongle in Ming Dynasty, in 1404, Zhu Di, the founder of Chengzu in Ming Dynasty, set up Tianjin Weicheng and built the Acropolis in Tianjin. The four sides of Tianjin began to take shape. So Zhu Di became the second person to thank Tianjin after Cao Cao. To be exact, he was the emperor to thank. Although the scale of Tianjin Acropolis was determined at that time, its walls were rammed and piled up, and were seriously damaged by rainwater. During the period of Hongzhi in Ming Dynasty, Simiancheng was rebuilt with Qingshi in Shandong Province, and an abacus city with a square nine miles, a height of three feet and a width of five feet was built. In the three years of Yongzheng in the Qing Dynasty, Emperor Yongzheng advocated the construction of waterways to facilitate the transportation of grain from Jiangsu and Zhejiang to the north, and to upgrade Tianjin from a defensive garrison to a large-scale state. In the ninth year of Yongzheng (1725), Yongzheng upgraded Tianjin to a prefecture with a more important position. Therefore, Emperor Yongzheng was the third emperor to whom Tianjin should be most grateful. Later, after continuous construction, the city wall was still the shape of the Hongzhi period of the Ming Dynasty, but there were also many residential areas and commercial centers outside the city. Until 1900, the Eight-Power Coalition invaded Tianjin, bombarded the southern city wall of Tianjin with guns, and opened the door to Beijing. During the two years under the rule of the eight-nation coalition forces in Tianjin, they dismantled the walls of the four-sided city of Tianjin, and, in accordance with the requirements of the Tianjin Treaty, also dismantled the Dagukou Fortress, making Tianjin an undefended city. The Anglo-French coalition demolished the wall of Tianjin, built four broad roads in the location of the wall, and paved trams around the city, which provided lights and tap water to the residents of the city. In the 1980s and 1990s, the Tianjin Municipal Government began the square transformation, demolishing most of the buildings in the old city, leaving only a few valuable historical buildings, including the Guangdong Guild Hall, the Children's Palace and the Temple of Confucius.