Shangjing Longquanfu

Shangjing Longquanfu or Sanggyeong Yongcheonbu, also known as Shangjing/Sanggyeong, Huhan/Holhan Fortress, is an archaeological site in Ning'an, Heilongjiang, China. It was the capital of the Balhae Kingdom from 756 to 785, and again from 793 to 926.The site is located in about 3 kilometres from the modern town of Dongjingcheng, and the ruined city is also colloquially called "Dongjingcheng". The site has been protected since the 1960s. The Chinese government has established the Bohai Shangjing National Archaeological Park and an archaeological museum at the site.

Source: Wikipedia