Around 221 BCE powerful Chinese emperor Shih Huang Ti has united the various parts of China. But on north of his empire in the desert lived barbarian tribes of nomads, and he felt that they pose a threat to his empire. Therefore, it is ordered to raise a large wall that will protect all the northern provinces of China.
Great Wall of China is indeed a huge project that was completed in only fifteen years. It was later extended and upgraded many times, but also partially destroyed . Nevertheless, there is still a large part of the wall.
Did the emperor managed to prevent incursions of nomads in China? Unfortunately no. Some of the wall still could be damaged. So the barbarians, called the Mongols, came through the damaged parts of the wall. Not only that, even Chinese themselves are damaged his wall. Chinese farmers have tilled the soil and sometimes off the wall.
Besides that, Great Wall has served ( and still serves ) as a boundary between the Chinese and Mongolian culture, between agricultural and nomadic lifestyles.
Great Wall is the longest wall in the world. If one takes into account all the yaw, length is over three thousand kilometers. Since it is a defensive wall it stretches along the mountain ridges and narrow gorge.
Great Wall of China was built of earth, stone and brick. The height is between 5 and 10 meters, and in regular intervals there are rising guard houses. Along the top of the wall has 4.5 meters wide trail.