World's longest tunnel completed under the French Alps

Swiss authorities are showing off an engineering feat - the world's longest tunnel has been completed.

It's located under the French Alps and connects Switzerland and Northern Italy.

Trains will speed through the 35-mile long tunnel at more than 150 mph.

It's been under construction since 1999, and more than 31 million tons of earth have been removed from the mountains. The project cost more than $10 billion.

Testing will begin in October, with the first passenger service slated to begin next June.