The file was well-prepared with the participation of prestigious foreign and local scientists, including those from the Vietnam-Japan Experts’ Joint Committee, the Ile region of France and UNESCO.

Authorized agencies will collect opinions on the file before sending it to UNESCO by September 30 at the latest.

In December 2002, the Vietnam Archaeology Institute started the excavation work on a 19,000 sq.m acreage at 18 Hoang Dieu street of Hanoi capital city to find out a precious relic site.

Researchers said the site was the centre of the Thang Long imperial citadel, the most important among ancient capitals of Vietnam, where the country’s most important rituals were held during the Ly, Tran and Le dynasties.

The royal citadel was recognized as a national historical and architectural relic site in late 2007.