Fengzhen Pass in the Gobi Desert, located North out of Datong in north Shanxi Province, is the first of three outer Great Wall passes in Shanxi. The other two Passes are Ningwu Guan and Pian Guan.
The Great Wall Inner Layer through Yanmen Guan has an adjoing section leading Northward to the village of Beibu (Beibao) where it inter-connects with the Outer Layer.
A Full Google Earth Supported Map Overview of All Structures of the Great Wall of China from East to West, by DrBen.Net (c) ChinaReport.com and Google.com.