The Great Wall of China is one of the largest building construction projects ever completed. The Great Wall stretches across the mountains of northern China, winding north and northwest of Beijing. It is constructed of masonry, rocks and packed-earth. It was over 5,000 km long. Its thickness ranged from about 4.5 to 9 meters and was up to 7.5 meters tall. This Great Wall can be seen from Earth orbit, but, contrary to legend, it is not visible from the moon, according to astronauts Neil Armstrong, Jim Lovell, and Jim Irwin.
After subjugating and uniting China from seven warring states, Emperor Qin Shi Huangdi connected and extended four old fortification walls along the north of China that originated about 700 BC, over 2500 years ago. Armies were stationed along the wall as a first line of defense against the invading nomadic Hsiung Nu tribes north of China, the Huns. Since then, the Great Wall has served as a monument of the Chinese nation throughout history. A visit to the Great Wall is like a tour through the history backwards; it brings tourists great excitement in each step of the wall.
The Great Wall of China is one of the greatest wonders of the world. Just like a gigantic dragon, the Great Wall winds up and down across deserts, grasslands, mountains and plateaus stretching from east to west of China. However, some sections of it are now in ruins. Still it stands out for its architectural grandeur and historical significance.
The construction of the Great Wall drew heavily on the local resources for construction materials. It was built in line with the local conditions by a great army of manpower composed of soldiers, prisoners, and local people. The Wall demonstrates the manifestation of the wisdom and tenacity of the Chinese people. The Great Wall has long been incorporated into Chinese mythology and popular symbolism.