The master piece of extreme engineering, the tunneling under the Alps.
The Gotthard Base Tunnel (GBT) is a railway tunnel through the Alps in Switzerland with scheduled commercial services from December 2016. The route length is 57.09 km (35.5 mi) and a total of 151.84 km (94.3 mi) of tunnels, shafts and passages, it is the longest and deepest traffic tunnel in the world and the first flat low-level route through the Alps.
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