The Great Wall of China
The Great Wall of China is a series of fortifications built across the historical northern borders of ancient Chinese States and Imperial China. It served as protection against invaders, as well as a form of border control through regulating both trade (by imposition of duties on goods transported along the Silk Road) and travel (immigration and emigration). While several walls were constructed from as far back as the 7 th Century BCE , around 220 BCE under the reign of Qin Shi Huang , the first emperor of China (reign: 221 BCE – 210 BCE), sections of the earlier constructions were joined to form the original Great Wall.