Six ancient cities buried deep underground and spanning several dynasties over 2,000 years, have been unearthed in Kaifeng, in the east of China's Henan province.

Archaeologists working at the Xinzheng Gate site, a gate on the wall of the ruins of Bianliang (Kaifeng's name during the Northern Song Dynasty, 960 to 1127), on March 11, 2017 [Photo: Xinhua]

The 2000-square-meter site boasts cultural relics from the Warring States Period (475-221 BC) to the Qing Dynasty (1644-1911), with each city piled one on top of another.

It includes city gates and walls form the Song Dynasty (960-1279), roads from the Song to the Qing Dynasties, civilian homes and courtyards from the Qing Dynasty, plus courtyard walls from Yuan Dynasty (1271-1368).

To carry out archaeological excavation and better protect the site, Kaifeng launched the "City upon a City" Xinzheng Gate project in 2012.

In ancient China, if a capital of a dynasty fell during conflict, the capital of the succeeding dynasty would be built in another place. The ruins of the previous capital would be abandoned, according to China Scenic.

As Kaifeng lies in the south bank of the Yellow River, subject to flooding, the ancient cities were buried by mud, and were stacked on top of each other.

As an ancient capital of various dynasties, Kaifeng boasts a history of more than 4,000 years.