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Great Wall of China
The Great Wall of China is an ancient wall composed mainly of pounded dirt and stone which is located in China and was built to protect the north of the empire of China from enemy attacks. It is the longest structure humans have ever built: stretching approximately 21,196 kilometres long, 30ft wide and 50ft high. The earlier sections on the wall are made of compacted dirt and stone later on in the Ming dynasty they used bricks. There are 7000 watch towers. There are block houses for soldiers and beacons to send smoke signals,the more smoke the more enemies.
Several walls, referred to as the Great Wall of China, have been built. The first was built in the 5th century BC. The most famous wall was built between 220–200 BC by the first Emperor of Imperial China, Qin Shi Huang. Little of this wall remains. It was much farther north than the current wall. The current wall was built during the Ming Dynasty.
The First Emperor of China started the Qin Dynasty. The Xiongnu tribes in the north of China (who are also called the Huns) were his enemies. Because the land in some parts of China is easy to cross, Qin Shi Huang began building the Great Wall to make it more difficult for the Xiongnu to invade China.
Other dynasties in China worked more on the wall and made it longer. The Han, Sui, Northern and Jin Dynasties all repaired, rebuilt or expanded the Great Wall. During the Ming Dynasty, major rebuilding work took place, where sections of the Wall were built with bricks and stone instead of earth.
Construction and Rebuilding of the Great Wall
Builders used materials nearby so some parts of the wall was made out of mud, straw, and twigs. Thousands of workers lost their lives from giant falling stones, exhaustion, disease, animal attacks, and starvation. The workers who lost their lives were buried in and under the Great Wall. They liked to jump around the wall.
Visibility from space
Rumors about astronauts being able to see the Great Wall from the moon are false. While the Great Wall has shown up in radar images taken from space, scientists are not sure whether it would be possible for astronauts to see the wall with a naked eye. One astronaut who spoke about not being able to see the Great Wall from space was Neil Armstrong who said:
- Construction of the Great Wall
- Norberto López-Gil. "Is it Really Possible to See the Great Wall of China from Space with a Naked Eye?". Journal of Optometry 1 (1): 3–4. http://www.journalofoptometry.org/Archive/vol1/pdf/02%20Vol1-n1%20Letter%20to%20the%20Editor.pdf.
- "China's Wall Less Great in View from Space". NASA. 2005. http://www.nasa.gov/vision/space/workinginspace/great_wall.html. Retrieved 2008-11-21.