The Great Wall of China is the name of a system of fortifications built along the north of China. They were constructed by the empire from the third century BC. for many centuries to stop the invasions of nomadic peoples of Mongolia. The Chinese call the construction "the Wall of Ten Thousands Li". Ten thousand symbolizes infinity in China, whereas Li is a unit of length, so the original name of the building can be translated as "Infinitely Long Wall". In reality, however, the Great Wall of China consists of many sections of varying lengths and heights, made of different materials at different times. The most renowned is the renovated fragment near Beijing, which is the obligatory point of every trip to the capital of China.