Kleven in Ukraine

Located near a town called Kleven in Ukraine, this 1.8-mile-long tree-covered tunnel is part of a private railway for trains delivering wood to a local factory. It has come to be called the "Tunnel of Love."

Nearly 15 1/4 miles long, Norway's Laerdal Tunnel opened in 2000 to link the cities of Aurland and Lærdal along the European highway known as E16. Inside the tunnel, drivers can stop at any of the three caves built to provide a break during the 20-minute drive underground. (Jorn Eriksson/flickr.com)