A watch tower at the Great Wall's Ningxia section, blanketed in snow. [Photo by Li Gonghe/chinadaily.com.cn]

Known as “the museum of the Great Wall” for its variety and diversity, the Ningxia section of the wall is 1,038 kilometers long, and was built as early as the Qin dynasties (221 BC-206 BC).

Weather-beaten and isolated, some of the sections are now in rather poor condition.