Qin Shi Huang, founder of the Qin dynasty, ruled a unified China as its first emperor from 221-207 B.C. Among the many massive building projects he ordered during his reign was the earliest version of China’s Great Wall, which ran along the country’s northern border and was designed to protect against barbarian invasions. But Emperor Qin’s most memorable project was the massive mausoleum complex he had constructed for himself near the ancient city of Xi’an. Guarded by an army of more than 6,000 life-size terra cotta soldiers, the emperor’s tomb would remain hidden for more than 2,200 years after his death.