12:48 Jun. 1, 2016
Tunnel is to be officially opened in Switzerland, after almost two decades of construction work.
The 57km (35-mile) twin-bore Gotthard base tunnel will provide a high-speed rail link under the Swiss Alps between northern and southern Europe.
Switzerland says it will revolutionise European freight transport.
Goods currently carried on the route by a million lorries a year will go by train instead.
The tunnel will overtake Japan's 53.9 km Seikan rail tunnel as the longest in the world and push the 50.5 km Channel Tunnel linking the UK and France into third place.
German Chancellor Angela Merkel, French President Francois Hollande and Italy's Prime Minister Matteo Renzi will join Swiss officials at the grand opening.
"It is just part of the Swiss identity," federal transport office director Peter Fueglistaler told Reuters news agency. Full story