Just how great?

The Wall gets measured

Just how great?

China's very own Maginot Line

The length of the Great Wall of China has often been a matter of conjecture. Over the years there has been considerable variance in estimates of its length. When Nixon visited China in 1972, Time magazine reckoned it to be 2,694km long. The Xinhua News Agency published a figure of 50,000km in 1979. A popular Chinese saying pinned it at 10,000 li (5,000km).

Well, at long last a definitive figure is now available. A two year mapping exercise by the State Administration of Cultural Heritage and the State Bureau of Surveying and Mapping has used modern methods – such as GPS and infrared range finders – to reach a definitive length. It is exactly 8,851.8km.

The survey analysed the section of wall that was built or restored in the Ming Dynasty (1368-1644). This wall stretches from Hushan in Liaoning to the Jiayu Pass in Gansu.

However, the measurement includes not just wall, but 359.7km of trenches and 2,232.5km of natural barriers (i.e. hills and rivers). The man-made bit measures 6,259.6km.

Defining what constitutes the wall has always been a challenge. John Man, who authored a book on China’s most famous landmark, says it most pithily: “The Great Wall is not always great, not a single wall, and not all in China.”

His research traces the wall as far as Mongolia, finding sections that even the locals have forgotten about – places where the wall has become an innocuous ridge. He also meets a man called Cheng Dalin who has spent 35 years photographing the wall and still thinks he has seen only 85% of it.

Little wonder then that Voltaire compared the Great Wall to the pyramids: both have their share of mysteries. In the wall’s case, precisely where do you measure its beginning and end?

What is known is that the wall was begun by the First Emperor in 214 BC, and was added to by successive dynasties. Its main purpose, in Man’s view, was to demarcate the country’s border with the tribes to the north and northwest. Given the number of times that China was overrun by northern tribes (Xiongnus, Mongols, Manchus ), the wall can hardly be classified as impregnable.

However, it was in the wake of the Mongol invasion that China’s next dynasty, the Ming decided to put together an edifice that might at least look like a bit more of a challenge to get past. In 1568 the task was given to Qi Jiguang, who became the architect of the section of wall you see on most postcards. He told the emperor: “In recent years the Wall has been annually repaired and annually destroyed. This is futile and unprofitable.”

Qi’s plan was to build fortified walls, stretching from north of Beijing to the sea. The Ming Dynasty spent the next 60 years building a wall with 1,017 forts that could garrison 160,000 troops.

It is this section that the UN recognised as a World Heritage Site in 1987, and it is the Ming section of the Wall that the survey focused on and measured.

Whether the survey has measured the whole wall or not, its main purpose seems to have been preservation. Shan Jixiang of the State Administration for Cultural Heritage says: “The Great Wall is under great threat. Climate change and the country’s massive infrastructure building being the two biggest threats. The survey was designed to map protection zones for the Ming Great Wall and keep records and files on the Wall’s upkeep.”

The survey will now focus on other sections of the Wall: those built by the Qin and Han Dynasties. Perhaps when that’s complete, we’ll finally know how long the Great Wall really is.

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