Nanjing is the capital of the Jiāngsū state. Is is located at 250 km from Shanghai. The city has been twice in its history the capital of China first in the XIVth century and then in the XXth century.
This town has a Ming heritage as the Linggu temple, the Ming Xiaoling Tomb or of course the Ming Palace ruins with its walls and gates.
There are also other momuments and things to visit as the Zijin Mountain, the Sun Yasten Mausoleum, the Presidential Palace or the Nanjing Museum.
In fact, Nanjing is a calmer city compared to Shanghai or Beijing with some visits or walk to do and is really close from Shanghai.