The Swiss are today celebrating the opening of the world's largest underground passage to mark its completion 17 years after construction began.
The €12bn £8.5bn Gotthard base tunnel is 57km 35 miles long and will overtake Japan's 53.85km Seikan railway tunnel to become the world's largest and deepest underground passage.
The completed tunnel travels up to 2.3km below the surface of the mountains above and through rock that reaches temperatures of 46 C without ventilation due to a high lithostatic pressure from rock above it – which can measure up to 2,500m in some sections*.
Federal transport office director Peter Fueglistaler told Reuters the tunnel was "a masterpiece of timing, cost and policy."
This morning a Catholic priest, a pastor, a rabbi and an imam were present for the ceremony, according to Swiss Info.
For those who are interested, the ventilation plan used 24 axial fans, six air locks – thus reducing local airflow needed and managing risks of smoke in the event of a fire – and 16 air barriers.