Great Wall of China
The wall was built to help keep out northern invaders like the Mongols. Smaller walls had been built over the years, but the first Emperor of China, Qin Shi Huang, decided that he wanted a single giant wall to protect his northern borders. The most well-known sections of the wall were built by Ming Dynasty. Genghis Khan, the founder of the Mongol Empire, was the only one who breached the Great Wall of China in its