China

The great wall of the First Emperor of Qin.

By the time he was 38 years old King Zheng of Qin had conquered the six major kingdoms between his kingdom and the east coast. He unified the kingdoms and switched his title from king to emperor by declared himself "Qin Shi Huang" (first emperor of Qin).

Qin's dynastry - pronounced "Chin" - became modern day China. The 13,000 miles of unified northern wall became the Great Wall of China.