Shanhaiguan or Shanhaikwan (both: shän-hĪ-gwän) [key] [Chin., = mountain sea door], city, NE Hebei prov., China, on the Bohai. Strategically situated where the Great Wall meets the sea and on the narrow coastal route to Manchuria, it has been the site of many battles and the route of many invasions. It now lies on a double-track railroad linking Tianjin with Shenyang (Mukden). The city was known as Haiyang until 1949. Another name is Linyu.