Artists perform during the grand opening for the tunnel, the world's longest and deepest rail tunnel. FABRICE COFFRINI/AFP/AFP/Getty Images
The 57km (35-mile) tunnel, which runs under the Swiss Alps, was first conceived in sketch-form in 1947. Construction began 17 years ago. FABRICE COFFRINI/AFP/AFP/Getty Images
Artists perform during the grand opening of the tunnel. FABRICE COFFRINI/AFP/AFP/Getty Images
A horse-drawn carriage parades during the opening of the tunnel. PETER KLAUNZER/AFP/AFP/Getty Images
From left to right, Italian PM Matteo Renzi, Swiss President Johann Schneider-Ammann, Germany Chancellor Angela Merkel and French President Francois Hollande on board the maiden voyage on the line. AFP/AFP/AFP/Getty Images
A guest poses with an umbrella decorated with the Swiss Rail clock logo before the opening ceremony of the Gotthard Base Tunnel. FABRICE COFFRINI/AFP/AFP/Getty Images
The first train comes out of the tunnel in Erstfeld. Laurent Gillieron/Keystone via AP