Driving through the Qinling Zhongnanshan Tunnel in central China is unlike entering an ordinary highway tunnel. For about 15 minutes, motorists travel beneath one of China's toughest mountain crossings, passing through an 18.02-kilometre underground route carved into the Qinling Mountains in Shaanxi Province.
The grey concrete ceiling suddenly transforms into glowing blue skies, fluffy white clouds and colourful lighting effects, creating the illusion that drivers have briefly emerged into daylight before continuing underground.
