Zhu says the excavations at the Yecheng site meanwhile give a boost to the studies of urban development between the Han and Tang dynasties, helping people to clearly picture the layout of imperial cities from the Kingdom of Wei, the Sixteen States period and the Northern Dynasty.

He says Yecheng was smartly planned when Cao Cao began to construct it in AD 204. "It was symmetric in respect of an axis, and it was divided into districts for different functions. The new model laid a foundation for the later building of Chang'an of the Sui and Tang dynasties, and extensively influenced the layout of ancient capitals in China and even East Asia."

Contact the writer at linqi@chinadaily.com.cn