The Great Wall of China is a series of fortification made of stone and other earth materials. It was constructed in several phases, and later joined which was eventually known as the Great Wall. Among those different parts, the most famous one is built by Qin Shi Huang, the first Emperor of China during 220-206 BC. The main purpose of the wall is to protect the Chinese empire from nomadic herds from the far northern steppe. It is one of the Seven Wonders of the World and can be seen from the moon.