The world's longest tunnel officially opened on Wednesday, with the trailblazing rail passage under the Swiss Alps aiming to ease transit through the heart of Europe.
With Europe's political unity shaken by a massive migrant crisis and the looming threat of Britain's EU exit, Swiss president Johan Schneider-Amman said the tunnel would "join the people and the economies" of Europe.
He spoke as the first train made a ceremonial run through the 57-kilometre (35-mile) Gotthard Base Tunnel (GBT) beneath the region's spectacular mountain peaks, with European leaders on board.
The tunnel took 17 years to build, at a cost of over 12 billion Swiss francs ($12 billion, 11 billion euros), with 125 labourers rotating in three shifts to lay the tunnel's slab track in 43,800 hours of non-stop work, according to the Swiss rail service.
German Chancellor Angela Merkel, French President Francois Hollande and Italian Prime Minister Matteo Renzi were among the passengers on the first train Wednesday.
The trio sat together in a first-class carriage, along with Schneider-Amman, and chatted over glasses of water through the 20-minute journey from Erstfeld in the central canton of Uri southward to Ticino canton.
Speaking at ceremony in the town Pollegio after the inaugural trip, Hollande urged British voters to recall their closeness to Europe on the June 23 Brexit vote.
"We are as united as we have ever been," Hollande said, drawing a parallel between the GBT and the 1994 opening of the Channel Tunnel, which connected Paris and London by high-speed rail and fostered fresh ties between the two capitals.
"I hope that the British will remember (that closeness) when the day comes" to cast their vote, he said.
Merkel told Swiss broadcaster ATS the network it was "marvellous" to think about taking a journey with 2000 metres of mountain rock above her head.
The tunnel was entirely funded by non-EU member Switzerland, but leaders from the bloc have hailed it for improving connectivity from Rotterdam to the Adriatic at a time when the continent's divisions have dominated headlines.
Travel through the picturesque Alpine region, by rail or by road, requires taking a zigzag and undulating route.
The Gotthard Base Tunnel was designed to offer a better option for both private travellers and commercial freights.
When the full service opens in December, the tunnel will shave the train journey from Zurich to Milan in northern Italy down to two hours and 40 minutes, roughly an hour less than it currently takes.
It should also make rail freight more efficient -- partly by supporting heavier cargo, reducing the number of smoke-spewing lorries on the roads and in turn improving traffic and curbing pollution.
The number of daily rail passengers is expected to increase from the current rate of 9,000 people to 15,000 by 2020, according to the Swiss federal railway service.
The rough design for a rail tunnel under the Gotthard Pass was first sketched by Swiss engineer Carl Eduard Gruner in 1947.
But bureaucratic delays, concerns over the cost and other hurdles pushed back the start of construction until 1999.
Wednesday's inauguration featured a ceremony with at times abstract choreography and elaborately costumed dancers, including an angel-type figure floating above orange-clad workers.
The Gotthard Tunnel was largely made possible by technical advances in tunnel-boring machines, which replaced the costly and dangerous blast-and-drill method.
The primary machine used to make the Gotthard tunnel was roughly 410-metres long and functioned like a mobile factory.
It cuts through rock and throws the debris backwards while simultaneously placing the pre-formed segments of concrete that form the shape of the tunnel.
A separate system grouts the pieces together.
With its official opening, the GBT has surpassed Japan's 53.9-kilometre Seikan tunnel as the world's longest train tunnel.
The 50.5-kilometre Channel Tunnel has been bumped into third place.