Co Loa is a large archaeological site located in the Bac Bo region of northern Vietnam, just outside of Hanoi. Today it is home to thousands of residents of the Co Loa commune. A mixture of legend, history, and archaeological research suggests that this was a fortified, political center for proto-Vietnamese civilization, likely being founded during the Dongson Culture (c. 600 BC – AD 200) period of Vietnam. The Dongson Culture is famous for its bronze working industry. The Co Loa site is marked by a series of three earthen rampart enclosures, the largest of which encompasses some four to five hundred hectares of landscape. The size and scale of the architectural features suggest construction by an early, powerful, and politically centralized society. Much of the ramparts remain standing today in various states of collapse. In some places, the walls stand ten meters in height and up to 30 meters in width.
However, archaeological fieldwork has helped clarify our understanding of this site. At present, there appears to have been three major chronological periods and five construction phases that use different construction techniques.
Interestingly, this area has been quite significant for Vietnamese civilization, as it has operated as a cultural and political center for millennia.