It is recorded that Suzhou City was originally the capital of State Wu during the Spring and Autumn Period (770-476 B.C.), which was built by Wu Zixu, a famous general and politician of State Wu, upon the commands of He Lv, King of State Wu, in the sixth year of the Reign of Emperor Jingwang (514 B.C) in Eastern Zhou Dynasty (770-256 B.C.). At that time, Pan Gate was one of the eight gates of ancient Suzhou, which was called Coiled Dragon Door, for a wooden Coiled Dragon was hung on the gate to deter and intimidate State Yue, the major rival of State Wu. The present structure was built in the eleventh year of the Reign of Zhizheng (1351) at the end of the Yuan Dynasty (1271-1368). The bulwark was expanded by Zhang Shicheng (one of the leaders of the Red Turban Rebellion in the late Yuan dynasty) in the sixteenth year of the Reign of Zhizheng(1356).
Pan Gate was once repaired in the early Ming Dynasty, the early and the late Qing Dynasty. The existing Pan Gate matches with the position shown in the stele Map of Pingjiang drawn in Southern Song Dynasty, and the overall layout and architectures are typical of the late Yuan Dynasty and the early Ming Dynasty. The land and water gates, positioned from north to south, parallel but staggered, are the only “Land cum Water Gate” of its kind in Suzhou that is entirely preserved.
The water gates comprise of inner and outer gates, which are 4.6 meters apart, with depth of 24.5 meters. They have their own typical structures, indicating that they were built at the different times. It is apparent that the outer gate was built earlier than the inner gate.
The land gates also comprise of double gates, inner and outer. In between of the double gates, there is a barbican, a nearly square city from planar view, with the inner circumference being 177 meters. The walls, 8.1 meter in height, are built on stone slab foundations and are constructed with bricks. To enhance the stability of the walls, some extra trapezoidal walls were built at both the right and left sides of the gate. Above the first arch are three openings in triangular array, which are holes for pouring water in when the enemy attached the city with fire. This gate was built in a very early time. On the north side of the walls is a ramp for people to mount the city. People can ascend to the wall tower walking from east to west.
From 1976 to 1981, the dilapidated land and water gates were repaired and reinforced, and what had been restored were parapet walls around the wall tower, forts and the mounting ramp. In 1983, the entire eastern wall, about 300 meters in length, was renovated. In 1986, a two-story three-bay tower, with hip roof and multiple eaves, was built on the original site of the old land gate tower.