The Great Wall of China is among the most recognisable human-made structures in the world. Stretching across deserts, mountains and plains, it runs for more than 21,000 kilometres in total and has stood, in one form or another, for well over two thousand years. Despite its name, however, it is not a single wall but a network of many walls, watchtowers and fortified passes built over many centuries.
The earliest sections date from the 7th century B.C.E., when separate Chinese kingdoms constructed defensive walls against both each other and the nomadic peoples of the northern steppes. When the First Emperor unified China in 221 B.C.E., he ordered that these regional walls be joined and extended into a single barrier. Enormous numbers of soldiers, prisoners and ordinary workers were forced into the project, and countless lives were lost.
Most of what modern visitors see today was actually built much later, under the Ming dynasty between the 14th and 17th centuries. The Ming engineers used brick and stone rather than the earlier earthen ramparts, producing the tall grey walls, elegant watchtowers and wide walkways that appear in photographs. The wall at this time served not only to block invaders but to monitor trade, control movement and transmit warnings over long distances using smoke signals.
The wall eventually lost its military importance when China was united with its former enemies under later dynasties. For centuries it was left to crumble, and local farmers even took stones from it for their own buildings. Today, the best-preserved sections are protected monuments, drawing millions of tourists each year and serving as a powerful symbol of Chinese identity.