Ten years ago, a big construction project finished. The Gotthard Base Tunnel in Switzerland is the longest and deepest tunnel in the world.

It opened in 2016 and connects northern and southern Europe by train. The train goes from the Netherlands to Italy.

It's called a Base Tunnel because it goes through the base of the mountain.

This means the train journey is mostly straight and flat.

The high-speed trains can go very fast, up to 250km/h.

Building the tunnel took 17 years and cost a lot of money, around £11.2 billion.

Workers removed a lot of rock using big machines and explosions.

A big drill was used to remove rocks during construction.

Before the tunnel, trains had to go slowly through the mountains.

Now, trains can go quickly through the mountain in just 20 minutes.

The tunnel is 57km long and very deep in some places.

At its deepest point, the train is 7,546 feet below the surface.

This is the deepest train tunnel in the world.

Many people have used the train since it was built.

In 2025, an average of 16,400 people used the train every day.