Great Wall of China

The Badaling Section of the Great Wall

Span of Wall: From Jiayu Pass in Gansu Province in the west to the mouth of the Yalu River in Liaoning Province in the east, Republic of China

The only man-made object to be visible from space and said to be visible from the Moon. At more than 2,000 years old  the Great Wall of China remains one of the great wonders of the world, an engineering feat rarely matched in the 22 centuries since its construction began. It was first built to protect an ancient Chinese empire from marauding tribes from the north. But it evolved into something far greater - a boon to trade and prosperity and ultimately a symbol of Chinese ingenuity and will. 

Great Wall of China, Chinese (Wade-Giles) WAN-LI CH'ANG-CH'ENG, or (Pinyin) WANLI CHANGCHENG ("10,000 Li Long Wall"), one of the largest building-construction projects ever carried out, running (with all its branches) about 4,000 miles (6,400 km) east to west from Po Hai, the northwestern arm of the Yellow Sea, to a point deep in central Asia. Parts of the vast fortification date from the 4th century BC. In 214 BC Shih Huang-ti, the first emperor of a united China, connected a number of existing defensive walls into a single system fortified by watchtowers, which served both to guard the rampart and to communicate with the capital, Hsien-yang, near Sian, by signal--smoke by day and fire by night. The principal enemy against whom the Great Wall was built were the Hsiung-nu, the nomadic tribes of the northern steppes. The Great Wall was originally constructed partly of masonry and partly of earth and was faced with brick in its eastern portion. It was substantially rebuilt in later times, especially in the 15th and 16th centuries. The basic wall is generally about 30 feet (9 m) high, and the towers are about 40 feet (12 m) high.

The Great Wall is actually a series of walls built and rebuilt by different dynasties over 1,000 years. And while they often served the same purpose, these walls reflected the worlds - both natural and cultural - in which they were erected. For all its seeming timelessness, the Great Wall is an emblem of China's evolution.

The Badaling section of the Great Wall snaking along the mountains northwest of Beijing was built at the beginning of the Ming Dynasty in the 14th century. Being 7.8 metres high and 5.8 metres wide at the top on the average, it has battle forts at important points, including the corners.

An interesting story is that Emperor Shih Huang Ti would not let people that died working on the wall have a proper burial. Instead, they were to be built into the wall to save time. Because of this, archeologists have discovered tombs built into the Great Wall.

Map showing span of the Great Wall and construction undertaken by Ming and Qin Dynasties