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The '''Great Wall of China''' is any of several extended frontier fortifications in northern China. These were constructed in ancient times as barriers against invading armies. The original wall was built in 220–206 BC by [[Qin Shi Huang]], the emperor who unified China. In modern times, this wall is no longer recognizable from the ground, but it has been mapped using satellite photography. The modern form of the Great Wall was built during the [[Ming dynasty]] (1368 - 1644). The claim that the wall can be seen from space is an urban legend.  

The '''Great Wall of China''' is any of several extended frontier fortifications in northern China. These were constructed in ancient times as barriers against invading armies. The original wall was built in 220–206 BC by [[Qin Shi Huang]], the emperor who unified China. In modern times, this wall is no longer recognizable from the ground, but it has been mapped using satellite photography. The modern form of the Great Wall was built during the [[Ming dynasty]] (1368 - 1644). The claim that the wall can be seen from space is an urban legend.  

The Great Wall winds some 2,400 km (1,500 mi) along the edge of the Mongolian plateau from Gansu Province in the west to the Yellow Sea in the east. Its width ranges from 4 to 12 m (12 to 40 ft) and its height from 6 to 15 m (20 to 50 ft). It makes possible much more effective military defense of China from invaders. It is 4,000 miles long and more than 20 feet tall.

The Great Wall winds some 2,400 km (1,500 mi) along the edge of the Mongolian plateau from Gansu Province in the west to the Yellow Sea in the east. Its width ranges from 4 to 12 m (12 to 40 ft) and its height from 6 to 15 m (20 to 50 ft). It makes possible much more effective military defense of China from invaders. It is 4,000 miles long and more than 20 feet tall.

The Mongols got passed the wall simply by bribing the guards.<ref>Hucker, Charles O.  ''China's Imperial Past: An Introduction to Chinese History and Culture.''  Stanford UP, 1997.</ref> In 1644, the Ming were overthrown by peasant rebels and a Ming general opened the Great Wall to the Manchu, who conquered China and founded the [[Qing dynasty]].

The Mongols got passed the wall simply by bribing the guards.<ref>Hucker, Charles O.  ''China's Imperial Past: An Introduction to Chinese History and Culture.''  Stanford UP, 1997.</ref> In 1644, the Ming were overthrown by peasant rebels and a Ming general opened the Great Wall to the Manchu, who conquered China and founded the [[Qing dynasty]].

It has been disputed whether it is even visible from low earth orbit. A 2008 article in Scientific American stated: "The unglamorous truth is that 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."<ref name="Hvistendahl" />

It has been disputed whether it is even visible from low earth orbit. A 2008 article in Scientific American stated: "The unglamorous truth is that 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."<ref name="Hvistendahl" />

In 2005 an [[American]] astronaut (of [[Chinese]] descent) succeeded in [[photograph]]ing the Wall. <ref>BBC News, Shanghai ''Great Wall visible in space photo'', by Francis Markus, 19 April, 2005 [http://news.bbc.co.uk/1/hi/world/asia-pacific/4459311.stm BBC News report of "China Daily" article 4/19/2005]</ref>  

In 2005 an [[American]] astronaut (of [[Chinese]] descent) succeeded in [[photograph]]ing the Wall.<ref>BBC News, Shanghai ''Great Wall visible in space photo'', by Francis Markus, 19 April 2005 [http://news.bbc.co.uk/1/hi/world/asia-pacific/4459311.stm BBC News report of "China Daily" article 4/19/2005]</ref>  

There is no truth to the notion that there are ''few'' human structures visible from space; Cecil Adams comments:

There is no truth to the notion that there are ''few'' human structures visible from space; Cecil Adams comments:

According to [[NASA]] director [[Adnan Lulla]], "A lot has been said and written about how visible the wall is. In fact, it is very, very difficult to distinguish the Great Wall of China in astronaut photography, because the materials that were used in the wall are similar in color and texture to the materials of the land surrounding the wall -- the dirt." <ref>http://www.nasa.gov/vision/space/workinginspace/great_wall.html</ref>

According to [[NASA]] director [[Adnan Lulla]], "A lot has been said and written about how visible the wall is. In fact, it is very, very difficult to distinguish the Great Wall of China in astronaut photography, because the materials that were used in the wall are similar in color and texture to the materials of the land surrounding the wall -- the dirt." <ref>http://www.nasa.gov/vision/space/workinginspace/great_wall.html</ref>

The Great Wall was listed as [[World Heritage]] by the [[UN]] in [[1987]].<ref>http://www.thegreatwall.com.cn/en </ref> Although long sections of the wall are now in ruins or have disappeared, it is still one of the more remarkable structures on earth and China's best-known monument.

The Great Wall was listed as [[World Heritage]] by the [[UN]] in [[1987]].<ref>http://www.thegreatwall.com.cn/en</ref> Although long sections of the wall are now in ruins or have disappeared, it is still one of the more remarkable structures on earth and China's best-known monument.

== References ==

== References ==