THE GREAT WALL OF CHINA

The Chinese were already familiar with the techniques of wall-building by the time of the Spring and Autumn Period, which began around the 7th century BC. During the Warring States Period from the 5th century BC to 221 BC, the states of Qi, Yan and Zhao 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.
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. Later, the Han, Sui, Northern and Jin dynasties all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders.
The Great Wall concept was revived again during the Ming Dynasty following the Ming army's defeat by the Oirats in the Battle of Tumu in 1449.
From Wikipedia, the free encyclopedia

The Great Wall of China, 1907
Herbert Ponting (1870-1935)
Original uploader was Janke at en.wikipedia
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Map of the Great Wall of China
Source: Jan, Michel / Michaud, Roland / Michaud, Sabrina: Die Chinesische Mauer, München 2000 (Hirmer)
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The Great Wall of China
Source originally posted to Flickr
Author Saad Akhtar from New Delhi, India
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An area of the sections of the Great Wall at Jinshanling
Author: Georgio
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Is it Really Possible to See the Great Wall of China from Space with a ...
(From: J Optom in journalofoptometry.org)

Great Wall of China as seen in a false-color radar image from the Space Shuttle,
taken in April 1994 by NASA
(From Wikipedia, the free encyclopedia):

A Ripley's Believe It or Not! cartoon from May 1932 claimed that the wall is "the mightiest work of man, the only one that would be visible to the human eye from the moon," and Richard Halliburton's 1938 book Second Book of Marvels makes a similar claim, but it is not true. This belief has persisted, assuming urban legend status, and sometimes even appeared in school textbooks. Arthur Waldron, author of The Great Wall of China: From History to Myth, has speculated that the belief might go back to the fascination with the "canals" once believed to exist on Mars.
The apparent width of the Great Wall from the moon is the same as that of a human hair viewed from 2 miles away. To see the wall from the moon would require spatial resolution 17,000 times better than normal (20/20) vision.[12] Not surprisingly, no lunar astronaut has ever claimed seeing the Great Wall from the moon.
Incidentially, if one could have seen the Great Wall from the moon, one ought to be able to see most of the roads in the world as well, given that they in total length far surpasses that of the great wall, and commonly are even wider. This is again not the case.
A more controversial question is whether the Wall is visible from low earth orbit, i.e an altitude of as little as 100 miles (160 km). NASA claims that it is barely visible, and only under nearly perfect conditions; it is no more conspicuous than many other man-made objects.[13] Other authors have argued that due to limitations of the optics of the eye and the spacing of photoreceptors on the retina, it is impossible to see the wall with the naked eye, even from low orbit, and would require visual acuity of 20/3 (7.7 times better than normal).
(From Wikipedia, the free encyclopedia)

A satellite image of the Great Wall of China.
The Great Wall, visible as a black line
running diagonally through the image
from lower left to upper right
Image courtesy NASA/GSFC/MITI/ERSDAC/JAROS,
and U.S./Japan ASTER Science Team
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Desktop available 1024x768
(Source: spacedaily.com)

Great Wall of China Wallpaper:
Click the size you would like to download:
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(Courtesy of © 1996-2008 National Geographic Society)

History of China
From Ancient China to Modern China circa 1988
by Leon Poon, University of Maryland

Political History of China
Beginnings and early history to modern era, circa 1988
by Leon Poon, UMD

Rupert Wingfield-Hayes, a BBC Beijing correspondent wrote on Wednesday, 30 July, 2003:
Most of the Great Wall of China is not as it appears on the television adverts and postcards.
Far from it. Most of the wall is in fact in a terrible state of repair.
It is overgrown, worn down by the elements and assaulted by locals who steal its stone.
In the last few years it has begun to be trampled too by hoards of hikers looking for a unique Great Wall experience.
Well, not any more, or so says the Chinese Government.
With nearly 3,000 kilometres of wall to choose from - most of it in remote, sparsely populated mountains - it is hard to see how local authorities are going to enforce their new ban.
The Great Wall of China is so spectacular that like the colossus at Rhodes and the Hanging Gardens of Babylon, it can be said to be one of the greatest wonders of the world. This is one of the largest manmade structures ever constructed and stretches across the mountains of Northern China surrounding the north and northwest sides of Beijing. The wall itself consists of masonry, rocks and packed earth.
Local villages and farms have used the great wall as a source of building materials over the last few centuries and as aerial photographs have shown, some sections of the great wall has only the top battlements still remaining, with the center of the wall being filled with sand and slit. Reconstruction and restoration of this amazing structure is, unfortunately, slow and problematic, as the same brutal conditions which originally made the Great Wall a triumph of engineering and determined planning are faced today.
(Copyright © 2007 China travel service itourschina.com)

(Image from great-wall-of-china.org)

A BRIEF HISTORY OF CHINA AND THE GREAT WALL:
With the continuous development of modern science and technology, we are learning more and more about the world we live in. We explore outer space to find out the secrets of the universe. We study our history to understand the stories that have taken place on the planet we live on. We try to learn to live in harmony with our environment, with other animals and plants. And most of all, we try to learn to live in peace with ourselves and with other human beings. Learning is an ongoing process for every individual as well as for all mankind. Based on what we currently know, below is a brief history of China and the Great Wall.

Chunqiu Period
770 B.C. - 476 B.C. In a divided China, many ducal states started to build walls along their boundaries.
Zhanguo Period
476 B.C. - 221 B.C.
Qin Dynasty
221 B.C. - 206 B.C. After unification, Qin linked and extended the walls of three northern states and formed the first Ten Thousand Li Great Wall (2 li = 1 km).
West Han Dynasty
206 B.C. - 25 A.D. Han further extended the Great wall to over 10,000 km.
East Han Dynasty
25 A.D. - 220 A.D.
Three Kingdoms Period
220 A.D. - 280 A.D.
West Jin Dynasty
265 A.D. - 316 A.D.
East Jin Dynasty
317 A.D. - 420 A.D.
South and North Dynasty
420 A.D. - 589 A.D. The states in the north continued to build the Great Wall.
Sui Dynasty
581 A.D. - 618 A.D. Sui also built the Great Wall.
Tang Dynasty
618 A.D. - 907 A.D.
Five Dynasties
907 A.D. - 960 A.D
North Song Dynasty
960 A.D. - 1127 A.D.
South Song Dynasty
1127 A.D. - 1276 A.D.
Yuan Dynasty
1271 A.D. - 1368 A.D.
Ming Dynasty
1368 A.D - 1644 A.D. Ming rebuilt the Great Wall, the length totalled over 6,000 km.
Qing Dynasty
1644 A.D. - 1911 A.D.
(Source: thegreatwall.com.cn)