Great Wall of China

The Great Wall developed from separate frontier walls and fortifications built by states in northern China. Around 220 BCE, the Qin ruler Qin Shi Huang connected sections of earlier defences into a broader system. Construction and repair continued under later dynasties, with routes, materials and purposes changing over time. The Great Wall is therefore not a single uninterrupted wall erected in one period, but a complex of structures built in different eras.

Much of the familiar masonry and brickwork dates from the Ming dynasty (1368–1644), when the frontier defence system was extensively strengthened. UNESCO describes the whole historic property as extending more than 20,000 kilometres, encompassing sections built over a long period; this is not the length of one continuous surviving wall. The Ming sections alone are commonly estimated at about 8,850 kilometres. The system included walls and natural barriers as well as passes, fortresses, watchtowers, shelters and routes for movement and signalling.

The fortifications were intended to help defend northern frontiers and manage movement across them. Their military role depended on garrisons, communications, terrain and broader state policy, not simply on the masonry itself. The Great Wall did not make the frontier impermeable: its history included raids, battles, negotiation and changing control of territory. The diverse sections reflect different political circumstances and strategies rather than one unchanging defensive plan.

The Great Wall was inscribed on the UNESCO World Heritage List in 1987. Its surviving fabric includes remains from multiple periods, from ancient rammed-earth fortifications to Ming-era masonry. UNESCO identifies its historical, strategic and architectural importance, while noting that protection must address the scale of the property, its cross-regional distribution and pressures associated with development and tourism. Many sections are damaged or have disappeared, making conservation a continuing concern.