After 17 years of construction, the world’s longest and deepest rail tunnel has opened today in Switzerland.
If you take into account the two main tubes that comprise the Gotthard Base Tunnel and its various shafts, cross passages and access tunnels, it actually has 152 km (94 mi) of tunnels in total. It is also said to have virtually no gradients.
The initial idea for the tunnel was conceived 68 years ago, but the plans were redrawn on a number of occasions. Once construction finally commenced, there were 2,400 workers on site at peak times. Nine workers also lost their lives during the build.