Switzerland has completed construction on the world's longest tunnel

The Swiss Alps are an unforgiving landscape of rugged, rocky peaks and lush, green valleys. Connecting communities that would be otherwise isolated by the vast mountain range- including cultural and economic hubs like Zurich, Milan and Turin-is no easy task.

Tunneling and track-laying for the 35-mile NEAT Gotthard Base Tunnel has been completed, making it officially the longest tunnel in the world, surpassing Japan's 14.5-mile Seikan Tunnel.

Swiss authorities held a media day inside the tunnel on August 24 to announce that the majority of technical work for the tunnel had been completed, Swiss newspaper TDG reports. Testing will begin October 1 in anticipation of the first passenger and freight trains in June 2016.