Another wonder of the Medieval World, the Great Wall of China is a series of stone and earthen fortifications built, rebuilt and maintained between the 5th century and 16th century to protect the northern borders of the Chinese Empire during the rule of the successive dynasties. The most famous wall was built by the first emperor of China, Oin Shi Huang. The Wall took on its present form during the Ming dynasty (1368-1644). The brick-and-granite work was enlarged, sophisticated designs were added, watch towers were redesigned and modern canon mounted in strategic areas.