In what is marvel of modern engineering marvel right in the heart of the majestic Alps, Switzerland on Wednesday opened the world's longest and deepest railway tunnel.

The 57.1-km (35.5 mile)-long Gotthard Base Tunnel which took 17 years to get built has been called as a symbol of European unity and has built at a cost of $12 billion.

It was built by 2,400 workers and more than 28 million tonnes of rock was used.

A worker at the construction site | Source: Reuters

Here are some of the pictures from the opening ceremony near Erstfeld town in Switzerland where a ceremonial run was held:

It was made after a referendum in which 64 percent of Swiss voters approved it.

Journalists walk in front of mock gates of the NEAT Gotthard Base Tunnel inside the event hall for the upcoming opening ceremony near the town of Erstfeld, Switzerland | Source: Reuters

It will reduce the travel time between Zurich to Milan in Italy by a little over an hour.

Swiss police officers stand beside of mock gates of the NEAT Gotthard Base Tunnel inside the event hall | Source: Reuters

It is expected to reduce the number of diesel trucks on road and decrease pollution.

A general view shows the northern gates (L) of the NEAT Gotthard Base Tunnel near the town of Erstfeld, Switzerland | Source: Reuters

The first ones to travel the tunnel at the official opening will be 500 lucky winners plus guests of the 130,000 who participated in a ticket lottery

A train drives past the northern gates of the Gotthard Base Tunnel near the town of Erstfeld, Switzerland | Source: Reuters

260 freight trains and 65 passenger trains will traverse the two-tube tunnel daily by the end of the year.

A police officer stand guards the north entrance of the new Gotthard Base Tunnel the world's longest train tunnel on the eve of its opening ceremony on May 31, 2016 in Attinghausen near Erstfeld | Source: AFP

15,000 people are expected to use it by 2020.

An Italian train makes its way at the north entrance of the new Gotthard Base Tunnel the world's longest train tunnel on the eve of its opening ceremony on May 31, 2016 in Erstfeld | Source: AFP

(Feature image source: AFP)