According to Ming Dynasty survey records, the Jin city walls had a perimeter of about 18 kilometers. Mongol rulers of the Yuan Dynasty destroyed the Jin capital. The sumptuous palaces were set ...

All of which makes Nanjing’s Ming City Walls (Nanjing Chengqiang)—the longest ever built at 35km—all the more remarkable. Nanjing was a walled city as far back at 2,500 years ago.

Say the word Xi'an, and people think of the Chinese city's astounding collection of terracotta warriors, created to guard the Emperor Qin Shi Huang's tomb in the third century B.C. But on a recent ...