The Great Wall of China, one of the worlds greatest wonders, was classified as a world heritage by UNESCO (United Nations Educational, Scientific, and Cultural Organization) in 1987.
Such a massive structure, the Great Wall stretches east to west in a snake-like pattern for more than 4100 miles(6400KM) through deserts, mountains, and the various other terrains of China.
In the beginning, the Great Wall was built by the chinese kingdoms of Yan, Zhao and Qin, for protection during times of war. The ruler of the Quin dynasty emperor QinShihuang unified China, and then was able to link the various discontinuations in the wall to form a complete wall on the northern border of china which protected against invasions from the Huns (you may have heard of Attila the Hun).
Since then, the Great Wall of China has had it's place in history as China's greatest monument.