In pics: ancient fortress complexes in north China

Aerial photo taken on July 7, 2020 shows an outdoor performance stage at Dijicheng historical site in Yangcheng County, north China's Shanxi Province. Built and developed during Ming Dynasty (1368-1644) and Qing Dynasty (1644-1911), Guoyu ancient city and Dijicheng historical site are typical ancient fortress complexes in north China. (Xinhua/Chai Ting)