Yongqing
Yongqing ( Chinese 永清县 , Pinyin Yǒngqīng Xiàn ) is a district in the prefecture -level city of Langfang in the Chinese province of Hebei . It has an area of 774 km² and has 370,000 inhabitants. Its main town is the large community of Yongqing (永清 镇).
The site of the border tunnel (Bianguan didao yizhi 边关 地道 遗址) - the so-called " Underground Great Wall " from the time of the Song Dynasty - has been on the list of monuments of the People's Republic of China (6-14) since 2006 .
Coordinates: 39 ° 19 ' N , 116 ° 29' E