The Great Wall of China is a series of fortifications made of stone, brick, tamped earth, wood, and other materials, generally built along an east-to-west line across the historical northern borders of China in order to protect the Chinese Empire or its prototypical states against intrusions by various nomadic groups.
In 221 BC, Emperor Qin Shihuang ordered the walls of the Qin, Zhao and Yan kingdoms in the north to be linked up and reinforced, after he united China. The extended new wall stretched from Lintao to Liaodong, with a total length of over20,000 li. It was during the Ming Dynasty that the Wall took on its present form. At that time, it stretched some 6,300 km from the Yalujiang River in the east to Jiayuguan Pass in the west, and is known as the Ten Thousand Li Wall.
The main construction of the Great Wall is a towering city wall stretching for thousands of miles, mostly built at the highest point of the mountain range, with a steep and majestic construction. It is the longest and largest military defense project built in the world. The Great Wall is a monument and crystallization of ancient Chinese culture and wisdom, and is one of the greatest architectural projects in the history of human civilization.
In 1987, UNESCO listed the Great Wall as a World Cultural Heritage site. Since the 20th century, there has been a saying that "the Great Wall is the only man-made structure on Earth that can be seen from space with the naked eye." The Great Wall of China is not only a historical and cultural relic, but also a unique natural landscape and a miracle of humanity. There is no ancient building in the world that is as long lasting, grand in scale, and costly as the Great Wall.
