At 15.23 miles, the Laerdal Tunnel is the longest tunnel in the world. Constructed between 1995 and 2000, it connects Laerdal to Aurland and serves as one of the major passages between Oslo and Bergen. The tunnel offers an alternative route for drivers who don't wish to deal with ferry connections or steep mountain passes, particularly during the winter.
Engineers took into account the potential "mental strain on drivers" from being in a tunnel for so long, so they divided it up into sections by putting in three mountain caves. These mountain cave sections are outfitted with yellow and blue lights, which are meant to mimic the sunrise, where the main sections of the tunnel have white lights. While there are no emergency exits, emergency phones and fire extinguishers have been placed every few hundred feet along the road.
Photo by Markus Trienke/Flickr