A car drives into a tunnel of Liupan Mountain, northwest China's Ningxia Hui Autonomous region, on July 3, 2016. As the longest highway tunnel in China's high altitude areas, the 9,485-meter Liupan Mountain Tunnel was opened to traffic Sunday, marking the completion of the Ningxia section of Qingdao-Lanzhou Highway. [Photo: Xinhua/Liu Hai]