Erstfeld (Switzerland) – Switzerland inaugurated the world’s longest and deepest rail tunnel through the heart of the Alps on Wednesday in an engineering marvel hailed as a symbol of European unity at a time of increasing fragmentation.

The 57.1-km long Gotthard Base Tunnel, 17 years under construction, is part of a 23 billion Swiss franc infrastructure project to speed passengers and cargo by rail under the mountain chain dividing Europe’s north and south.

The European leaders hailed the project as an inspiration for all who want to live the dream of people circulating freely.

Swiss President Johann Schneider-Ammann said he would gently press German Chancellor Angela Merkel, Italian Prime Minister Matteo Renzi and French President Francois Hollande to compromise in a standoff over Swiss plans to launch unilateral curbs on EU immigration.

“We will come closer personally and that is decisive,” he told reporters, adding that talks would resume in earnest after Britain’s June 23 vote to decide whether it should quit EU.

High-speed trains will whisk passengers in 17 minutes through the tunnel, a passage that took days until the first Alpine rail route opened in 1882. Around 260 freight trains and 65 passenger trains can traverse the two-tube tunnel daily once final testing ends later this year.

The Swiss threw an opening party that drew the leaders of all its neighboring countries in a show of European solidarity.

The inauguration party was attended by a priest, a rabbi, and an imam, who walked into the tunnel to bless it amidst strict security measures as more than 2,000 soldiers were mobilized to watch carefully the air space.

The tunnel along Europe’s main rail line connecting the ports of Rotterdam in the north to Genoa in the south snakes through the mountains as much as 2.3 km below the surface and through rock as hot as 46 degrees Celsius (114.8°F).

The old rail route crosses the pass in a series of loops and tunnels. The new flat route means even heavy trains will need only one locomotive rather than two or three.

Engineers had to dig and blast through 73 kinds of rock as hard as granite and as soft as sugar. Nine workers died.

The first travelers through the tunnel were 500 lucky winners plus guests who entered a lottery for the trip.

The European Union contributed in funding the tunnel by about 15 percent from the total value amounting to 12.2 billion Swiss francs.

Swiss voters also supported the project in several referendums in the 1990s.