It was once said the Great Wall was the only human structure visible from the moon. Although we now know that was a myth, the Great Wall remains one of the wonders of the world, winding more than 21,000 kilometers along the ancient borders of China from west to east. This series of fortifications dating back to about the 11th century BC is arguably the greatest manmade structure in the world.
The construction of the Great Wall can be traced back to as early as the Western Zhou Dynasty (1046-771 BC), built over centuries to protect the Chinese states and empires against the raids and invasions of various nomadic groups in the north. The early walls were later expanded, connected, reinforced and rebuilt over centuries.
Especially famous is the wall built in 220–206 BC by Qin Shi Huang, the first emperor of China. Yet most of the existing walls today were actually built during the Ming Dynasty (1368-1644). That also includes the “South-Great Wall” in Fenghuang County in Hunan Province, which is believed to be a fortification against the ethnic groups like Miao in the Ming Dynasty. According to the National Administration of Cultural Heritage, nearly 9,000-kilometers of the still-existing Great Walls in 2012 was the Ming Great Wall, along with sections built in the pre-Qin Period (21 century-221 BC), the Qin Dynasty (221-207 BC) and the Han Dynasty (202 BC-AD 220).
The Great Wall was listed on UNESCO’s World Cultural Heritage in 1987.
Rather than a simple wall as its name might indicate, the Great Wall is actually a military defense system composed of walls, passes, signal towers and fortresses.
Terrains where it is easy to defend yet hard to invade were widely chosen for the Great Wall construction, such as mountain ridges and cliffs.
The walls, as the major part of the fortification system, average 7.8 meters high, while some parts were built even higher if it was set on a plain or strategic pass. The walls are usually positive trapezoid in cross-section, with a 6.5-meter-wide bottom and 5.8-meter-wide top. A 4-5-meter-wide path was often set on the wall that allowed two parallel to pass.
Battlements line the uppermost portion of the vast majority of the wall, with defensive gaps of about 30 centimeters tall and 23 centimeters wide. From the parapets, guards could survey the surrounding land. There were also crenels — indentations or cutouts — to enhance the defense.
Crucial gates were set on defending terrain, such as mountain valleys, river turns or the only passes on a plain, such as the famous Shanhai Pass in Hebei Province, Zhenbeitai Pass in Shaanxi Province and Jiayu Pass in Gansu Province.
Signal towers were part of a crucial message transmission system. It is called “Feng Sui” in Chinese, which refers to the two different alarm types used at the border. “Feng” means smoke, while “sui” indicates lighting a fire, which is for message-transmission at night.
It is said that different smoke and fire numbers were used to report enemy numbers.
In the Ming Dynasty, firecrackers were added to enhance the alarm and accelerate message transmission. One smoke signal and one firecracker sound indicated about 100 enemy fighters; two smoke signals and two firecrackers suggested about 500 fighters.
A signal tower was usually set upon hill tops or other high points every 10 li (5,000 meters) to ensure their visibility.
On some parts of the Great Wall built in the Ming dynasty, towers were set every 5 li (2,500 meters). Guards at every beacon tower would copy the messages they saw until it reached the capital.
Apart from delivering messages, the tower also provided shelter and accommodation for envoys passing by.
There is a tale about the beacon towers and an unjust ruler widely known among the Chinese.
King You of the Western Zhou Dynasty was infatuated with a beauty named Baosi who hardly smiled.
To entertain the beauty, the king ordered lighting the beacon towers which was supposed to be a sign for invasion and calling help from the vassal states.
The beauty did laugh when witnessing all the feudal lords rushing to the capital Haojing in today’s Xi’an in Shaanxi Province with their armies for nothing.
But the feudal lords lost their trust in the king and the beacon towers after several such incidents.
When the nomadic army did actually invade, no feudal lords came as they thought the smoke signals were another joke of the king.
When the lords finally confirmed about the invasion and came to help, they found the king slaughtered, the capital destroyed and most territories in the west occupied by the nomadic group.
Hence, the new king moved the capital to Luoyi in today’s Luoyang in Henan Province and started the Eastern Zhou Dynasty (770-256 BC).
Before the use of bricks, the Great Wall was mainly built from rammed earth, stones and wood.
During the Ming Dynasty, however, bricks were heavily used in many areas of the wall, as were materials such as tiles, limes, and stones.
The size and weight of the bricks made them easier to work with than earth and stone, so construction quickened. Additionally, bricks could bear more weight and endure better than rammed earth.
Stones can hold under its own weight better than bricks, but are more difficult to use. Stones cut in rectangular shapes were used for the foundation, inner and outer brims, and gateways of the wall.
After guarding the nation for thousands of years, the Great Wall began fading — not only militarily, but physically as well.
Apart from the famous Badaling, Mutianyu and a handful of other heavily-visited tourist sections, “the wild wall” in untraversed areas is vanishing.
Erosion from wind and rain, plundering of bricks by nearby villagers and scrambling over parts of the wild wall by adventurous tourists are wreaking havoc. A report by the National Administration of Cultural Heritage in 2012 suggests that 22 percent of the Ming Great Wall has disappeared.