The broad grey ramparts and turreted watchtowers of The Great Wall rising over green mountains create an unforgettable symbol of power, and of China’s long and illustrious history.

Ferdinand Verbiest, a 17th century Jesuit scholar employed by the Manchu Qing government, declared that ‘the seven wonders of the world put together are not comparable to this work’. In 1935, Mao Zedong wrote, ‘No man is a hero unless he’s been to The Great Wall.’ In 1778, Samuel Johnson said that visiting The Great Wall would benefit future generations: ‘There would be a lustre reflected upon them from your spirit and curiosity. They would be at all times regarded as the children of a man who had gone to visit the wall of China.’

The Great Wall is a misnomer. It is not one, but many, many walls, built from the seventh century BC to the 16th century, and stretching, often doubling up, between the semi-desert of Gansu province in China’s northwest and the steep cliffs of eastern Shandong province, where a rampart tumbles down into the sea. Estimates of the length of this massive collection of walls range from 6,350 kilometres to 21,196 kilometres (a recent figure made possible by modern archaeological technology).

The brick walls of Hebei and Shandong provinces are very different from the yellow-earth walls in Gansu, and to some extent they served different purposes. Some of the earliest walls, built for defence as separate states evolved in the north of China from the seventh century BC, were linked and improved by China’s first emperor in the third century BC, when he overcame all the other warring states and created a unified China.

But it was during the subsequent Han dynasty (206 BC-220 AD) that the wall was extended, along the Silk Road into Gansu, reflecting the westward expansion of Han China into Central Asia. At the end of the Han dynasty, wall building stopped for more than 1,000 years as the Chinese state perceived little danger from invasion. The next great period of wall building was during the Ming dynasty (1368-1644) when various northern groups such as the Mongols and the Manchus presented a serious military threat.

Here are four different walls in four very different places that each tell us something about the history of China.