Nanjing Ancient City Wall, constructed during the Yuan and Ming Dynasties between 1365 and 1386, originally stretched over 30 km which made it the longest city wall in the world. Now, with about two thirds of the wall still intact, it still remains the longest city wall in China. It reaches all the way from the North end of Xuanwu Lake to the south-west corner of Purple Mountain. It snakes along the edge of Qin Huai River and heads back north all the way up to Yuejiang Tower.
 
The wall, designed by the first emperor of the Ming Dynasty (1368-1644) Emperor Zhu Yuan Zhang, was erected to protect the city, just as a mother does with her child, holding it closely in her arms. At the time, Nanjing served as the capital of China which lasted for six dynasties. Today it is still one of the Four Great Capitals in China.

Nanjing's Ancient City Wall is the most telling witness of the history and the crystallization of science, technology, military, architecture and art.