Great Wall of China

The Great Wall of China is a system of fortifications built across the historical northern borders of the Chinese states and Imperial China, raised to defend against nomadic incursions from the Eurasian Steppe. The earliest sections date to the seventh century BC, when individual states built separate walls that the Qin dynasty later joined into one connected system. Successive dynasties extended and rebuilt the wall over the following two millennia, and the best known and best preserved sections date from the Ming dynasty, 1368 to 1644. Rather than one continuous structure, it is a network of walls, towers and passes running across mountains, deserts and grassland.