, the front entrance to the
Forbidden City, with two protruding wings. in Suzhou, a combined land-and-water gate , showing both entrances of a combined land-and-water gate
Material The oldest form of wall construction in China was of
rammed earth. Stone rubble was used for the foundation. Bricks were also used but were less common. From the
Zhou dynasty, bricks were made of adobe, until the
Han dynasty, when baked bricks became common. It is not certain how common brick faced walls were during the
Shang and Zhou dynasties. In the state of
Xia (Sixteen Kingdoms), the
Xiongnu engineer Chigan Ali had the workers bake bricks for wall construction, and if a hammer blow could make a depression in them an inch deep, he would have the responsible worker killed. He also had the earth used to make the wall boiled with rice to harden it. While Chinese city walls always had an earthen core, the outer facings could be of either baked bricks laid in lime mortar, or stone where it was commonly available, such as in
Sichuan. Bricks were also used for constructing the sewer network below the
Beijing city wall in the 16th century. In addition to tamped earth, Chinese walls were sometimes reinforced with wood. A study of Han forts in
Xinjiang found that they had brushwood and poplar interspersed between the layers of tamped earth.
Dimensions Remains of city walls have been found as early as 15th century BC during the
Shang dynasty, which constructed large walls around the site of Ao with dimensions of in width at the base and enclosed an area of some squared. Walls of similar dimensions are also found at the ancient capital of the state of
Zhao,
Handan (founded in 386 BC), with a width of at the base, a height of , and a length of along its two rectangular sides. At the
Former Han capital of
Chang'an, the city wall constructed around 200 BC by Yang Yangcheng was 15m tall and 12m wide. It was also protected by a moat 45m wide with a depth of 4.5m. During the
Yuan dynasty,
Suzhou's walls were over 7m tall and, 11m thick at the base, and 5m thick at the top. During the
Ming dynasty, prefectural and provincial capital walls were thick at the base and at the top. Most Chinese walls were sloped rather than vertical. Sometimes the walls were raised on a plinth or supporting platform. Aside from the wall itself were attached watch towers and gate towers, usually two or three stories tall. Wall bricks came in many dimensions depending on regional variations. In the north, 30 cm x 23 cm x 15 cm was the most common, and in the south, 15 cm x 13 cm x 3 cm. Long-term strategic considerations meant that the walls of important cities often enclosed an area much larger than existing urban areas in order to ensure excess capacity for growth, and to secure resources such as timber and farmland in times of war. The city wall of
Quanzhou in
Fujian still contained one quarter vacant land by 1945. The city wall of Suzhou by the
Republic of China era still enclosed large tracts of farmland. The
City Wall of Nanjing, built during the Ming dynasty, enclosed an area large enough to house an airport, bamboo forests, and lakes in modern times.
Gates Gates were placed symmetrically along the walls. The principal gate was traditionally located at the centre of the south wall. Gatehouses were generally built of
wood and brick, which sat atop a raised and expanded section of the wall, surrounded by crenellated battlements. A tunnel ran under the gatehouse, with several metal gates and wooden doors.
Camouflaged defensive positions are placed along the tunnel (in an effect similar to
murder holes). Gatehouses were accessed by ramps, called
horse ramps or bridle paths, (), which sat against the wall adjacent to the gate.
Barbican An "archery tower" was often placed in front of the main gatehouse, forming a
barbican (). In its final form during the Ming and Qing dynasties, the archery tower was an elaborate construction, of comparable height to the main gatehouse, which stands some distance in front of the main gatehouse. At its base was a gate. The archery tower is so-named because of its rows of archery (and later cannon) placements, from which defenders could fire projectiles on attackers. Auxiliary walls, running perpendicularly to the main wall, connect the archery tower with the main gatehouse, enclosing a rectangular area. This area serves as a buffer zone, should the first gate be breached. Its Chinese name, "jar walls", refers to the intended strategy whereby attackers coming through the archery tower would be trapped in the barbican, open to attack from all sides. In large gates there may be multiple barbicans – the main gate of Nanjing (
Gate of China, Nanjing) had three barbicans, forming the most elaborate system still in existence in China.
Towers Towers that protruded from the wall were located at regular intervals along the wall. Large and elaborate towers, called corner towers (角楼,
Jiǎolóu), were placed where two walls joined (i.e. at corners). These were significantly higher than the wall itself, and gave defenders a bird's eye view over both the city and its surroundings.
Moat In larger cities, a
moat surrounded the wall. This could be connected to canals or rivers both in the city and outside, thus providing both a defense and a convenient transportation route. Nearby waterways might be adopted or altered to connect to, or form part of, the moat. ==Effectiveness against artillery==