How long is the Great Wall of China?

13,170 miles

Answer: Thanks to the modern measuring techniques, and after an archaeological survey taking more than five years, the total length of the world’s largest man-made structure had been finally revealed in 2012, as 13,170.69 miles. The surprising length is more than twice as long as the previous estimates. The Great Wall was started in 500 BC and first linked up under leader Qin Shi Huang in about 220 BC to protect China’s northern border and fend off foreign invaders.