Located 50 kilometers west of Ningwu county, north China's Shanxi province, Luyashan ice cave was formed in the glacial epoch in the quaternary period 3 million years ago. The climate condition outside the cave doesn't facilitate the form of ice; however, the ice pillars inside the cave never thaw. It is also the biggest ice cave discovered so far in China. [China.org.cn/Photo by Dong Nianlong]