Great Wall of China

Great Wall of China

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The Great Wall of China is a series of stone and earthen fortification
Fortification
Fortifications are military constructions and buildings designed for defence in warfare and military bases. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs...

s in northern China, built originally to protect the northern borders of the Chinese Empire
History of China
Chinese civilization originated in various regional centers along both the Yellow River and the Yangtze River valleys in the Neolithic era, but the Yellow River is said to be the Cradle of Chinese Civilization. With thousands of years of continuous history, China is one of the world's oldest...

 against intrusions by various nomadic groups. Several walls have been built since the 5th century BC that are referred to collectively as the Great Wall, which has been rebuilt and maintained from the 5th century BC through the 16th century. One of the most famous is the wall built between 220–206 BC by the first Emperor of China
Emperor of China
The Emperor of China refers to any sovereign of Imperial China reigning between the founding of Qin Dynasty of China, united by the King of Qin in 221 BCE, and the fall of Yuan Shikai's Empire of China in 1916. When referred to as the Son of Heaven , a title that predates the Qin unification, the...

, Qin Shi Huang
Qin Shi Huang
Qin Shi Huang , personal name Ying Zheng , was king of the Chinese State of Qin from 246 BC to 221 BC during the Warring States Period. He became the first emperor of a unified China in 221 BC...

. Little of that wall remains; the majority of the existing wall was built during the Ming Dynasty
Ming Dynasty
The Ming Dynasty, also Empire of the Great Ming, was the ruling dynasty of China from 1368 to 1644, following the collapse of the Mongol-led Yuan Dynasty. The Ming, "one of the greatest eras of orderly government and social stability in human history", was the last dynasty in China ruled by ethnic...

.

The Great Wall stretches from Shanhaiguan
Shanhaiguan District
Shanhaiguan District is a district of the city of Qinhuangdao, Hebei province, People's Republic of China, named after the pass of the Great Wall within the district, Shanhai Pass...

 in the east, to Lop Lake in the west, along an arc that roughly delineates the southern edge of Inner Mongolia
Inner Mongolia
Inner Mongolia is an autonomous region of the People's Republic of China, located in the northern region of the country. Inner Mongolia shares an international border with the countries of Mongolia and the Russian Federation...

. The most comprehensive archaeological survey, using advanced technologies, has concluded that all the walls measure 8851.8 km (5,500.3 mi). This is made up of 6259.6 km (3,889.5 mi) sections of actual wall, 359.7 km (223.5 mi) of trenches and 2232.5 km (1,387.2 mi) of natural defensive barriers such as hills and rivers.

The early walls


The Chinese were already familiar with the techniques of wall-building
Wall
A wall is a usually solid structure that defines and sometimes protects an area. Most commonly, a wall delineates a building and supports its superstructure, separates space in buildings into rooms, or protects or delineates a space in the open air...

 by the time of the Spring and Autumn Period, which began around the 8th century BC. During the Warring States Period
Warring States Period
The Warring States Period , also known as the Era of Warring States, or the Warring Kingdoms period, covers the Iron Age period from about 475 BC to the reunification of China under the Qin Dynasty in 221 BC...

 from the 5th century BCE to 221 BCE, the states of Qin
Qin (state)
The State of Qin was a Chinese feudal state that existed during the Spring and Autumn and Warring States Periods of Chinese history...

, Wei
Wei (state)
The State of Wei was a Zhou Dynasty vassal state during the Warring States Period of Chinese history. Its territory lay between the states of Qin and Qi and included parts of modern day Henan, Hebei, Shanxi and Shandong...

, Zhao
Zhao (state)
Zhao was a significant Chinese state during the Warring States Period, along with six others...

, Qi
Qi (state)
Qi was a powerful state during the Spring and Autumn Period and Period of the Warring States in ancient China. Its capital was Linzi, now part of the modern day city of Zibo in Shandong Province....

, Yan
Yan (state)
Yān was a state during the Western Zhou, Spring and Autumn and Warring States Periods of Chinese history. Its capital was Ji...

 and Zhongshan
Zhongshan (state)
Zhongshan was a Di state created by the nomadic Xianyu tribe in China during the later Zhou Dynasty, in the Chinese written sources it is referred to as a state of the Bai Di .)...

 all constructed extensive fortifications to defend their own borders. Built to withstand the attack of small arms such as swords and spears, these walls were made mostly by stamping earth and gravel between board frames.

Qin Shi Huang
Qin Shi Huang
Qin Shi Huang , personal name Ying Zheng , was king of the Chinese State of Qin from 246 BC to 221 BC during the Warring States Period. He became the first emperor of a unified China in 221 BC...

 conquered all opposing states and unified China in 221 BCE, establishing the Qin Dynasty
Qin Dynasty
The Qin Dynasty was the first imperial dynasty of China, lasting from 221 to 207 BC. The Qin state derived its name from its heartland of Qin, in modern-day Shaanxi. The strength of the Qin state was greatly increased by the legalist reforms of Shang Yang in the 4th century BC, during the Warring...

. Intending to impose centralized rule and prevent the resurgence of feudal lords, he ordered the destruction of the wall sections that divided his empire along the former state borders. To protect the empire against intrusions by the Xiongnu
Xiongnu
The Xiongnu were ancient nomadic-based people that formed a state or confederation north of the agriculture-based empire of the Han Dynasty. Most of the information on the Xiongnu comes from Chinese sources...

 people from the north, he ordered the building of a new wall to connect the remaining fortifications along the empire's new northern frontier. Transporting the large quantity of materials required for construction was difficult, so builders always tried to use local resources. Stones from the mountains were used over mountain ranges, while rammed earth
Rammed earth
Rammed earth, also known as taipa , tapial , and pisé , is a technique for building walls using the raw materials of earth, chalk, lime and gravel. It is an ancient building method that has seen a revival in recent years as people seek more sustainable building materials and natural building methods...

 was used for construction in the plains. There are no surviving historical records indicating the exact length and course of the Qin Dynasty walls. Most of the ancient walls have eroded away over the centuries, and very few sections remain today.
The human cost of the construction is unknown, but it has been estimated by some authors that hundreds of thousands,
if not up to a million, workers died building the Qin wall. Later, the Han
Han Dynasty
The Han Dynasty was the second imperial dynasty of China, preceded by the Qin Dynasty and succeeded by the Three Kingdoms . It was founded by the rebel leader Liu Bang, known posthumously as Emperor Gaozu of Han. It was briefly interrupted by the Xin Dynasty of the former regent Wang Mang...

, Sui
Sui Dynasty
The Sui Dynasty was a powerful, but short-lived Imperial Chinese dynasty. Preceded by the Southern and Northern Dynasties, it ended nearly four centuries of division between rival regimes. It was followed by the Tang Dynasty....

, and Northern dynasties all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders. The Tang
Tang Dynasty
The Tang Dynasty was an imperial dynasty of China preceded by the Sui Dynasty and followed by the Five Dynasties and Ten Kingdoms Period. It was founded by the Li family, who seized power during the decline and collapse of the Sui Empire...

 and Song
Song Dynasty
The Song Dynasty was a ruling dynasty in China between 960 and 1279; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty. It was the first government in world history to issue banknotes or paper money, and the first Chinese government to establish a...

  Dynasties did not build any walls in the region. The Liao
Liao Dynasty
The Liao Dynasty , also known as the Khitan Empire was an empire in East Asia that ruled over the regions of Manchuria, Mongolia, and parts of northern China proper between 9071125...

, Jin, and Yuan
Yuan Dynasty
The Yuan Dynasty , or Great Yuan Empire was a ruling dynasty founded by the Mongol leader Kublai Khan, who ruled most of present-day China, all of modern Mongolia and its surrounding areas, lasting officially from 1271 to 1368. It is considered both as a division of the Mongol Empire and as an...

 dynasties, who ruled Northern China throughout most of the 10-13th centuries, had their original power bases north of the Great Wall proper; accordingly, they would have no need throughout most of their history to build a wall along this line. The Liao carried out limited repair of the Great Wall in a few areas, however the Jin did construct defensive walls in the 12th century, but those were located much to the north of the Great Wall as we know it, within today's Inner
Inner Mongolia
Inner Mongolia is an autonomous region of the People's Republic of China, located in the northern region of the country. Inner Mongolia shares an international border with the countries of Mongolia and the Russian Federation...

 and Outer Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

.

The Ming era


The Great Wall concept was revived again during the Ming Dynasty
Ming Dynasty
The Ming Dynasty, also Empire of the Great Ming, was the ruling dynasty of China from 1368 to 1644, following the collapse of the Mongol-led Yuan Dynasty. The Ming, "one of the greatest eras of orderly government and social stability in human history", was the last dynasty in China ruled by ethnic...

 in the 14th century, and following the Ming army's defeat by the Oirats
Oirats
Oirats are the westernmost group of the Mongols who unified several tribes origin whose ancestral home is in the Altai region of western Mongolia. Although the Oirats originated in the eastern parts of Central Asia, the most prominent group today is located in the Republic of Kalmykia, a federal...

 in the Battle of Tumu in 1449. The Ming had failed to gain a clear upper hand over the Manchuria
Manchuria
Manchuria is a historical name given to a large geographic region in northeast Asia. Depending on the definition of its extent, Manchuria usually falls entirely within the People's Republic of China, or is sometimes divided between China and Russia. The region is commonly referred to as Northeast...

n and Mongolian tribes after successive battles, and the long-drawn conflict was taking a toll on the empire. The Ming adopted a new strategy to keep the nomadic tribes out by constructing walls along the northern border of China. Acknowledging the Mongol control established in the Ordos Desert
Ordos Desert
The Ordos Desert is a desert and steppe region lying on a plateau in the south of the Inner Mongolian Autonomous Region of the People's Republic of China . The soil of the Ordos is a mixture of clay and sand and, as a result, is poorly suited for agriculture. It extends over an area of...

, the wall followed the desert's southern edge instead of incorporating the bend of the Huang He.

Unlike the earlier Qin fortifications, the Ming construction was stronger and more elaborate due to the use of bricks and stone instead of rammed earth. As Mongol raids
Mongol invasions
Mongol invasions progressed throughout the 13th century, resulting in the vast Mongol Empire which covered much of Asia and Eastern Europe by 1300....

 continued periodically over the years, the Ming devoted considerable resources to repair and reinforce the walls. Sections near the Ming capital of Beijing were especially strong.

During the 1440s–1460s, the Ming also built a so-called "Liaodong Wall". Similar in function to the Great Wall (whose extension, in a sense, it was), but more basic in construction, the Liaodong Wall enclosed the agricultural heartland of the Liaodong province, protecting it against potential incursions by Jurched-Mongol Oriyanghan from the northwest and the Jianzhou Jurchens
Jianzhou Jurchens
The Jianzhou Jurchens were a grouping of the Jurchens as identified by the Chinese of the Ming Dynasty. They were the southernmost group of the Jurchen people The Jianzhou Jurchens (Chinese:建州女真) were a grouping of the Jurchens as identified by the Chinese of the Ming Dynasty. They were the...

 from the north. While stones and tiles were used in some parts of the Liaodong Wall, most of it was in fact simply an earth dike with moats on both sides.

Towards the end of the Ming Dynasty, the Great Wall helped defend the empire against the Manchu
Manchu
The Manchu people or Man are an ethnic minority of China who originated in Manchuria . During their rise in the 17th century, with the help of the Ming dynasty rebels , they came to power in China and founded the Qing Dynasty, which ruled China until the Xinhai Revolution of 1911, which...

 invasions that began around 1600. Even after the loss of all of Liaodong
Liaoning
' is a province of the People's Republic of China, located in the northeast of the country. Its one-character abbreviation is "辽" , a name taken from the Liao River that flows through the province. "Níng" means "peace"...

, the Ming army under the command of Yuan Chonghuan
Yuan Chonghuan
Yuan Chonghuan was a famed patriot and military commander of the Ming Dynasty who battled the Manchus in Liaoning. A commander of Cantonese origin, Yuan Chonghuan was known to have excelled in artillery warfare and successfully incorporated Western tactics with those of the East...

 held off the Manchus at the heavily fortified Shanhaiguan
Shanhai Pass
Shanhai Pass , or Shanhaiguan, along with Jiayu Pass and Juyong Pass, is one of the major passes of the Great Wall of China It is located in Shanhaiguan District, Qinhuangdao, Hebei. In 1961, Shanhaiguan became a site of China First Class National Cultural Site.It is a popular tourist destination,...

 pass, preventing the Manchus from entering the Chinese heartland. The Manchus were finally able to cross the Great Wall in 1644, after Beijing had fallen to Li Zicheng's rebels, and the gates at Shanhaiguan were opened by the commanding Ming general Wu Sangui
Wu Sangui
Wu Sangui was a Ming Chinese general who was instrumental in the succession of rule to the Qing Dynasty in 1644...

, who hoped to use the Manchus to expel the rebels from Beijing. The Manchus quickly seized Beijing, and defeated both the rebel-founded Shun Dynasty
Shun Dynasty
The Shun Dynasty was an imperial dynasty created in the brief lapse from Ming to Qing rule in China. The dynasty was founded in Xi'an on 8 February 1644, the first day of the lunar year, by Li Zicheng, the leader of a large peasant rebellion. Li, however, only went by the title of King, not Emperor...

 and the remaining Ming resistance
Southern Ming Dynasty
The Southern Ming Dynasty was the Ming loyalist regime that continued in Southern China from 1644 to 1662 following the capture of Beijing by rebel armies and the death of the last Ming emperor in 1644....

, establishing the Qing Dynasty
Qing Dynasty
The Qing Dynasty was the last dynasty of China, ruling from 1644 to 1912 with a brief, abortive restoration in 1917. It was preceded by the Ming Dynasty and followed by the Republic of China....

 rule over all of China.

In 2009, an additional 290 km (180.2 mi) of previously undetected portions of the wall, built during the Ming Dynasty, were discovered. The newly discovered sections range from the Hushan
Hushan Great Wall
Hushan Great Wall is the most easterly known part of the Great Wall of China. About 600 metres of remains were excavated here in 1989. In 1992, a section of wall was renovated and is open to the public, forming a popular tourist attraction. The wall runs for about 1,200 metres over Hushan...

 mountains in the northern Liaoning
Liaoning
' is a province of the People's Republic of China, located in the northeast of the country. Its one-character abbreviation is "辽" , a name taken from the Liao River that flows through the province. "Níng" means "peace"...

 province, to Jiayuguan in western Gansu
Gansu
' is a province located in the northwest of the People's Republic of China.It lies between the Tibetan and Huangtu plateaus, and borders Mongolia, Inner Mongolia, and Ningxia to the north, Xinjiang and Qinghai to the west, Sichuan to the south, and Shaanxi to the east...

 province. The sections had been submerged over time by sandstorms which moved across the arid region.

Under Qing rule, China's borders extended beyond the walls and Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

 was annexed into the empire, so construction and repairs on the Great Wall were discontinued. On the other hand, the so-called Willow Palisade
Willow Palisade
Willow Palisade was a system of ditches and embankments planted with willows intended to restrict movement into Manchuria, built by the Qing Dynasty during the later 17th century...

, following a line similar to that of the Ming Liaodong Wall, was constructed by the Qing rulers in Manchuria. Its purpose, however, was not defense but rather migration control.

Early Western reports of the wall


The North African traveler Ibn Battuta
Ibn Battuta
Abu Abdullah Muhammad Ibn Battuta , or simply Ibn Battuta, also known as Shams ad–Din , was a Muslim Moroccan Berber explorer, known for his extensive travels published in the Rihla...

, who was in Guangzhou
Guangzhou
Guangzhou , known historically as Canton or Kwangchow, is the capital and largest city of the Guangdong province in the People's Republic of China. Located in southern China on the Pearl River, about north-northwest of Hong Kong, Guangzhou is a key national transportation hub and trading port...

 ca. 1346, inquired among the local Muslims about the wall that, according to the Qur'an
Qur'an
The Quran , also transliterated Qur'an, Koran, Alcoran, Qur’ān, Coran, Kuran, and al-Qur’ān, is the central religious text of Islam, which Muslims consider the verbatim word of God . It is regarded widely as the finest piece of literature in the Arabic language...

, Dhul-Qarnayn
Dhul-Qarnayn
Dhul-Qarnayn , literally "He of the Two Horns" or "He of the two centuries" is a figure mentioned in the Qur'an, the sacred scripture of Islam, where he is described as a great and righteous ruler who built a long wall that keeps Gog and Magog from attacking the people who he met on his journey...

 had built to contain Gog and Magog
Gog and Magog
Gog and Magog are names that appear primarily in various Jewish, Christian and Muslim scriptures, as well as numerous subsequent references in other works. Their context can be either genealogical or eschatological and apocalyptic, as in Ezekiel and Revelation...

. Ibn Battuta reported that the wall was "sixty days' travel" from the city of Zeitun
Quanzhou
Quanzhou is a prefecture-level city in Fujian province, People's Republic of China. It borders all other prefecture-level cities in Fujian but two and faces the Taiwan Strait...

 (Quanzhou); Hamilton Alexander Rosskeen Gibb
Hamilton Alexander Rosskeen Gibb
Sir Hamilton Alexander Rosskeen Gibb , also commonly referred to as "H. A. R. Gibb", was a Scottish historian on Orientalism.-Early life and education:...

 noted Ibn Battuta has confused the Great Wall of China with that built by Dhul-Qarnayn.
This indicated that Arabs may have heard about China's Great Wall during earlier periods of China's history, and associated it with the Gog and Magog wall of the Qur'an. But, in any event, no one of Ibn Battuta's Guangzhou interlocutors had seen the wall or knew anyone who had seen it, which implies that by the late Yuan the existence of the Great Wall was not in the people's living memory, at least not in the Muslim communities in Guangzhou.

Soon after Europeans reached the Ming China in the early 16th century, accounts of the Great Wall started to circulate in Europe, even though no European was to see it with his own eyes for another century. Possibly the earliest description of the wall, and its significance for the defense of the country against the "Tartars" (i.e. Mongols), may be the one contained in the Third Década of João de Barros
João de Barros
João de Barros , called the Portuguese Livy, is one of the first great Portuguese historians, most famous for his Décadas da Ásia , a history of the Portuguese in India and Asia.-Early years:...

' Asia (published 1563). Interestingly, Barros himself did not travel to Asia, but was able to use Chinese books brought to Lisbon by Portuguese traders. One of the earliest records of a Western traveler entering China via a Great Wall pass (Jiayuguan, in this case) may be that of the Portuguese Jesuit brother Bento de Góis, who had reached China's north-western gate from India in 1605.

Notable areas





Some of the following sections are in Beijing municipality, which were renovated and which are regularly visited by modern tourists today.
  • "North Pass" of Juyongguan
    Juyongguan
    Juyongguan or Juyong Pass is located in an -long valley named "Guangou" which is inside Changping County more than from Beijing City. It is one of the three greatest passes of the Great Wall of China. The other two passes are Jiayuguan and Shanhaiguan....

     pass, known as the Badaling
    Badaling
    Badaling is the site of the most visited section of the Great Wall of China, approximately northwest of urban Beijing city in Yanqing County, which is within the Beijing municipality. The portion of the wall running through the site was built during the Ming Dynasty, along with a military...

    . When used by the Chinese to protect their land, this section of the wall has had many guards to defend China’s capital Beijing. Made of stone and bricks from the hills, this portion of the Great Wall is 7.8 metres (25.6 ft) high and 5 metres (16.4 ft) wide.
  • "West Pass" of Jiayuguan (pass). This fort is near the western edges of the Great Wall.
  • "Pass" of Shanhaiguan
    Shanhai Pass
    Shanhai Pass , or Shanhaiguan, along with Jiayu Pass and Juyong Pass, is one of the major passes of the Great Wall of China It is located in Shanhaiguan District, Qinhuangdao, Hebei. In 1961, Shanhaiguan became a site of China First Class National Cultural Site.It is a popular tourist destination,...

    . This fort is near the eastern edges of the Great Wall.
  • One of the most striking sections of the Ming Great Wall is where it climbs extremely steep slopes. It runs 11 kilometres (6.8 mi) long, ranges from 5 to 8 meters (16–26 ft) in height, and 6 metres (19.7 ft) across the bottom, narrowing up to 5 metres (16.4 ft) across the top. Wangjinglou is one of Jinshanling
    Jinshanling
    Jinshanling , a section of the Great Wall of China located in the mountainous area in Luanping County, 125 km northeast of Beijing. This section of the wall is connected with the Simatai section to the east. Some distance to the west lies the Mutianyu section...

    's 67 watchtowers, 980 metres (3,215.2 ft) above sea level.
  • South East of Jinshanling
    Jinshanling
    Jinshanling , a section of the Great Wall of China located in the mountainous area in Luanping County, 125 km northeast of Beijing. This section of the wall is connected with the Simatai section to the east. Some distance to the west lies the Mutianyu section...

    , is the Mutianyu
    Mutianyu
    Mutianyu is a section of the Great Wall of China located in Huairou County 70km northeast of Beijing. The Mutianyu section of the Great Wall is connected with Jiankou in the west and Lianhuachi in the east...

     Great Wall which winds along lofty, cragged mountains from the southeast to the northwest for approximately 2.25 kilometers (about 1.3 miles). It is connected with Juyongguan Pass to the west and Gubeikou to the east. west of the Liao Tian Ling stands apart of Great Wall which is only 2~3 stories high. According to the records of Lin Tian, the wall was not only extremely short compared to others, but it appears to be silver. Archeologists explain that the wall appears to be silver because the stone they used were from Shan Xi, where many mines are found. The stone contains extremely high levels of metal in it causing it to appear silver. However, due to years of decay of the Great Wall, it is hard to see the silver part of the wall today.


Another notable section lies near the eastern extremity of the wall, where the first pass of the Great Wall was built on the Shanhaiguan
Shanhai Pass
Shanhai Pass , or Shanhaiguan, along with Jiayu Pass and Juyong Pass, is one of the major passes of the Great Wall of China It is located in Shanhaiguan District, Qinhuangdao, Hebei. In 1961, Shanhaiguan became a site of China First Class National Cultural Site.It is a popular tourist destination,...

 (known as the “Number One Pass Under Heaven”). 3 km north of Shanhaiguan is Jiaoshan Great Wall, the site of the first mountain of the Great Wall. 15 km northeast from Shanhaiguan, is the Jiumenkou, which is the only portion of the wall that was built as a bridge.

Characteristics


Before the use of bricks, the Great Wall was mainly built from rammed earth
Rammed earth
Rammed earth, also known as taipa , tapial , and pisé , is a technique for building walls using the raw materials of earth, chalk, lime and gravel. It is an ancient building method that has seen a revival in recent years as people seek more sustainable building materials and natural building methods...

, stones, and wood. During the Ming Dynasty, however, bricks were heavily used in many areas of the wall, as were materials such as tile
Tile
A tile is a manufactured piece of hard-wearing material such as ceramic, stone, metal, or even glass. Tiles are generally used for covering roofs, floors, walls, showers, or other objects such as tabletops...

s, lime
Lime (mineral)
Lime is a general term for calcium-containing inorganic materials, in which carbonates, oxides and hydroxides predominate. Strictly speaking, lime is calcium oxide or calcium hydroxide. It is also the name for a single mineral of the CaO composition, occurring very rarely...

, and stone. 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. Stone can hold under its own weight better than brick, but is more difficult to use. Consequently, stones cut in rectangular shapes were used for the foundation, inner and outer brim
Brim
Brim refers to an edge or border*Brim *Brim , a defunct brand of decaffeinated coffee*Brim, Victoria is a town in Australia*Undercurrent, an award-winning 2010 Icelandic film...

s, and gate
Gate
A gate is a point of entry to a space enclosed by walls, or a moderately sized opening in a fence. Gates may prevent or control entry or exit, or they may be merely decorative. Other terms for gate include yett and port...

ways of the wall. Battlement
Battlement
A battlement in defensive architecture, such as that of city walls or castles, comprises a parapet , in which portions have been cut out at intervals to allow the discharge of arrows or other missiles. These cut-out portions form crenels...

s line the uppermost portion of the vast majority of the wall, with defensive gaps a little over 30 cm (11.8 in) tall, and about 23 cm (9.1 in) wide.

Condition



While some portions north of Beijing and near tourist centers have been preserved and even extensively renovated, in many locations the Wall is in disrepair. Those parts might serve as a village playground or a source of stones to rebuild houses and roads. Sections of the Wall are also prone to graffiti
Graffiti
Graffiti is the name for images or lettering scratched, scrawled, painted or marked in any manner on property....

 and vandalism
Vandalism
Vandalism is the behaviour attributed originally to the Vandals, by the Romans, in respect of culture: ruthless destruction or spoiling of anything beautiful or venerable...

. Parts have been destroyed because the Wall is in the way of construction.

More than 60 km (37.3 mi) of the wall in Gansu
Gansu
' is a province located in the northwest of the People's Republic of China.It lies between the Tibetan and Huangtu plateaus, and borders Mongolia, Inner Mongolia, and Ningxia to the north, Xinjiang and Qinghai to the west, Sichuan to the south, and Shaanxi to the east...

 province may disappear in the next 20 years, due to erosion from sandstorms
Dust storm
A dust / sand storm is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Particles are transported by saltation and suspension, causing soil to move from one place and deposition...

. In places, the height of the wall has been reduced from more than five meters (16.4 ft) to less than two meters. The square lookout towers that characterize the most famous images of the wall have disappeared completely. Many western sections of the wall are constructed from mud
Mudbrick
A mudbrick is a firefree brick, made of a mixture of clay, mud, sand, and water mixed with a binding material such as rice husks or straw. They use a stiff mixture and let them dry in the sun for 25 days....

, rather than brick and stone, and thus are more susceptible to erosion.

Watchtowers and barracks


Communication between the army units along the length of the Great Wall, including the ability to call reinforcements and warn garrisons of enemy movements, was of high importance. Signal towers were built upon hill tops or other high points along the wall for their visibility.

Visibility from the moon


One of the earliest known references to this myth appears in a letter written in 1754 by the English antiquary William Stukeley
William Stukeley
William Stukeley FRS, FRCP, FSA was an English antiquarian who pioneered the archaeological investigation of the prehistoric monuments of Stonehenge and Avebury, work for which he has been remembered as "probably... the most important of the early forerunners of the discipline of archaeology"...

. Stukeley wrote that, "This mighty wall of four score miles in length (Hadrian's Wall
Hadrian's Wall
Hadrian's Wall was a defensive fortification in Roman Britain. Begun in AD 122, during the rule of emperor Hadrian, it was the first of two fortifications built across Great Britain, the second being the Antonine Wall, lesser known of the two because its physical remains are less evident today.The...

) is only exceeded by the Chinese Wall, which makes a considerable figure upon the terrestrial globe, and may be discerned at the moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

." The claim was also mentioned by Henry Norman
Henry Norman
Sir Henry Norman, 1st Baronet PC was an English journalist and Liberal politician. Norman was educated privately in France and at Harvard University, where he obtained his B.A...

 in 1895 where he states "besides its age it enjoys the reputation of being the only work of human hands on the globe visible from the moon." The issue of "canals" on Mars was prominent in the late 19th century and may have led to the belief that long, thin objects were visible from space. The claim that the Great Wall is visible also appears in 1932's Ripley's Believe it or Not strip and in Richard Halliburton
Richard Halliburton
Richard Halliburton was an American traveler, adventurer, and author. Best known today for having swum the length of the Panama Canal and paying the lowest toll in its history—thirty-six cents—Halliburton was headline news for most of his brief career...

's 1938 book Second Book of Marvels.

The claim the Great Wall is visible has been debunked many times,"Can you see the Great Wall of China from the moon or outer space?", Answers.com. Accessed May 12, 2010.
Cecil Adams
Cecil Adams
Cecil Adams is a name, possibly a pseudonym, designating the American author of The Straight Dope, a popular question and answer column published in The Chicago Reader since 1973. Ed Zotti is Adams' current editor....

, "Is the Great wall of China the only manmade object byou can see from space?", The Straight Dope. Accessed May 12, 2010.
Snopes, "Great wall from space", last updated July 21, 2007. Accessed May 12, 2010.
"Is China's Great Wall Visible from Space?", Scientific American, February 21, 2008. "... the wall is only visible from low orbit under a specific set of weather and lighting conditions. And many other structures that are less spectacular from an earthly vantage point—desert roads, for example—appear more prominent from an orbital perspective." but is still ingrained in popular culture. The wall is a maximum 9.1 m (29.9 ft) wide, and is about the same color as the soil surrounding it. Based on the optics of resolving power (distance versus the width of the iris: a few millimeters for the human eye, meters for large telescopes) only an object of reasonable contrast to its surroundings which is 70 mi (112.7 km) or more in diameter (1 arc-minute) would be visible to the unaided eye from the moon, whose average distance from Earth is 384393 km (238,851.3 mi). The apparent width of the Great Wall from the moon is the same as that of a human hair viewed from 2 miles (3.2 km) away. To see the wall from the moon would require spatial resolution 17,000 times better than normal (20/20) vision. Unsurprisingly, no lunar astronaut has ever claimed to have seen the Great Wall from the moon.

Visibility from low earth orbit


A more controversial question is whether the Wall is visible from low earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

 (an altitude of as little as 100 miles (160.9 km)). NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 claims that it is barely visible, and only under nearly perfect conditions; it is no more conspicuous than many other man-made objects. Other authors have argued that due to limitations of the optics of the eye and the spacing of photoreceptors on the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...

, it is impossible to see the wall with the naked eye, even from low orbit, and would require visual acuity
Visual acuity
Visual acuity is acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain....

 of 20/3 (7.7 times better than normal).

Anecdotal reports


Astronaut William Pogue thought he had seen it from Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

 but discovered he was actually looking at the Grand Canal of China
Grand Canal of China
The Grand Canal in China, also known as the Beijing-Hangzhou Grand Canal is the longest canal or artificial river in the world. Starting at Beijing, it passes through Tianjin and the provinces of Hebei, Shandong, Jiangsu and Zhejiang to the city of Hangzhou...

 near Beijing. He spotted the Great Wall with binoculars
Binoculars
Binoculars, field glasses or binocular telescopes are a pair of identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes when viewing distant objects...

, but said that "it wasn't visible to the unaided eye." U.S. Senator Jake Garn
Jake Garn
Edwin Jacob "Jake" Garn is an American politician, a member of the Republican Party, and served as a U.S. Senator representing Utah from 1974 to 1993...

 claimed to be able to see the Great Wall with the naked eye from a space shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

 orbit in the early 1980s, but his claim has been disputed by several U.S. astronauts. Veteran U.S. astronaut Gene Cernan has stated: "At Earth orbit of 100 miles (160.9 km) to 200 miles (321.9 km) high, the Great Wall of China is, indeed, visible to the naked eye." Ed Lu
Ed Lu
Edward Tsang "Ed" Lu , is an American physicist and a former NASA astronaut. He is a veteran of two Space Shuttle missions and an extended stay aboard the International Space Station.-Education:...

, Expedition 7
Expedition 7
Expedition 7 was the seventh expedition to the International Space Station.-Crew:-Mission parameters:*Perigee: 384 km*Apogee: 396 km*Inclination: 51.6°*Period: 92 min...

 Science Officer aboard the International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...

, adds that, "it's less visible than a lot of other objects. And you have to know where to look."

In 2001, Neil Armstrong
Neil Armstrong
Neil Alden Armstrong is an American former astronaut, test pilot, aerospace engineer, university professor, United States Naval Aviator, and the first person to set foot upon the Moon....

 stated about the view from Apollo 11
Apollo 11
In early 1969, Bill Anders accepted a job with the National Space Council effective in August 1969 and announced his retirement as an astronaut. At that point Ken Mattingly was moved from the support crew into parallel training with Anders as backup Command Module Pilot in case Apollo 11 was...

: "I do not believe that, at least with my eyes, there would be any man-made object that I could see. I have not yet found somebody who has told me they've seen the Wall of China from Earth orbit. ...I've asked various people, particularly Shuttle guys, that have been many orbits around China in the daytime, and the ones I've talked to didn't see it."
In October 2003, Chinese astronaut Yang Liwei
Yang Liwei
Yáng Lìwěi is a Chinese major general and military pilot and a CNSA astronaut. He was the first man sent into space by the Chinese space program and his mission, Shenzhou 5, made China the third country to independently send people into space.-Background:...

 stated that he had not been able to see the Great Wall of China. In response, the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

 (ESA) issued a press release reporting that from an orbit between 160 and 320 km, the Great Wall is visible to the naked eye. In an attempt to further clarify things, the ESA published a picture of a part of the “Great Wall” photographed from Space. However, in a press release a week later (no longer available in the ESA’s website), they acknowledged that the "Great Wall" in the picture was actually a river.

Leroy Chiao
Leroy Chiao
Dr. Leroy Chiao , is an American engineer, former NASA astronaut, entrepreneur, motivational speaker and engineering consultant. Chiao flew on three shuttle flights, and was the commander of Expedition 10, where he lived on board the International Space Station from October 13, 2004 to April 24,...

, a Chinese-American astronaut, took a photograph from the International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...

 that shows the wall. It was so indistinct that the photographer was not certain he had actually captured it. Based on the photograph, the China Daily
China Daily
The China Daily is an English language daily newspaper published in the People's Republic of China.- Overview :China Daily was established in June 1981 and has the widest print circulation of any English-language newspaper in the country...

later reported that the Great Wall can be seen from space with the naked eye, under favorable viewing conditions, if one knows exactly where to look. However, the resolution of a camera can be much higher than the human visual system, and the optics much better, rendering photographic evidence irrelevant to the issue of whether it is visible to the naked eye.

See also

  • Chinese city wall
    Chinese city wall
    Chinese city walls refer to civic defensive systems used to protect towns and cities in China in pre-modern times. The system consisted of walls, towers, and gates, which were often built to a uniform standard throughout the Empire....

  • Defense of the Great Wall
    Defense of the Great Wall
    The Defense of the Great Wall was a campaign between the armies of Republic of China and Empire of Japan, which took place before the Second Sino-Japanese War officially commenced in 1937...

  • Economic history of China
    Economic history of China
    China's economic system before the late-1990s, with state ownership of certain industries and central control over planning and the financial system, has enabled the government to mobilize whatever surplus was available and greatly increase the proportion of the national economic output devoted to...

  • Great Wall Marathon
  • Great Wall of China hoax
    Great Wall of China hoax
    The Great Wall of China hoax was a faked story, published in United States newspapers on June 25, 1899, about bids by American businesses to demolish the Great Wall of China and construct a road in its place....

  • Great Wall of Qi
    Great Wall of Qi
    The Great Wall of Qi is the oldest existing Great Wall in China. Construction of the wall started in 685 BCE by the state of Qi, to defend itself against an invasion by the Kingdom of Chu. The existing sections date back to 500 BCE. Construction ended during the Warring States Period...

  • Green Wall of China
    Green Wall of China
    The Green Wall of China, also known as the Green Great Wall or Great Green Wall , will be a series of human-planted forest strips in the People's Republic of China, designed to hold back the expansion of the Gobi Desert...

  • List of World Heritage Sites in China
  • Military history of China before 1911

Further reading


  • Arnold, H.J.P, "The Great Wall: Is It or Isn't It?" Astronomy Now, 1995.
  • Hessler, Peter. "Walking the Wall". The New Yorker, May 21, 2007, pp. 56–65.
  • Lovell, Julia. The Great Wall: China against the World. 1000 BC – 2000 AD. London: Atlantic Books; Sydney, Australia: Picador, 2006. ISBN 978-0330-42241-3; ISBN 0-330-42241-3.
  • Michaud, Roland (photographer); Sabrina Michaud (photographer), & Michel Jan, The Great Wall of China. Abbeville Press, 2001. ISBN 0-7892-0736-2
  • Rojas, Carlos. The Great Wall: A Cultural History (Harvard University Press; 2010) 213 pages; traces the history and considers its imagery in literature, art, and other realms.
  • Waldron, Arthur, The Great Wall of China: From History to Myth. Cambridge: Cambridge University Press, 1990.


External links