The Alps are a big mountain range in Europe. They stretch 1,200km across eight countries.

In the past, people crossed the Alps on foot or by mule. They wanted to travel, trade, and fight wars.

The Romans fought to control the routes through the Alps. Hannibal and Napoleon also led armies over the mountains.

The Gotthard Base Tunnel is a new route through the Alps. It opened in 2016 and cost about £11.5bn.

Steel rings hold up the tunnel under the Alps.

The tunnel is important for travel and goods transport. It reduces travel time by up to an hour.

The Gotthard tunnel is 57km long and takes 20 minutes to cross. It is 2.3km deep, like some of the deepest mines.

Trains can go 155mph through the tunnel due to their design.

The Gotthard tunnel is flat, unlike older tunnels that spiral up the mountains.

The tunnel took 17 years to build.

The Gotthard tunnel is the longest in the world, beating the Channel Tunnel by 7km.

It is 3km longer than Japan's Seikan rail tunnel.

The new tunnel replaced the old Gotthardbahn rail tunnel from 1882.

Plans for the new tunnel started in the 1980s and took 17 years to complete.

The tunnel's steel rings prevent it from collapsing under the mountain's weight.

A massive 410m-long drill carved through the mountain at 40m per day.