Gotthard Base Tunnel (Switzerland) – Regular rail service began in December 2016 through Switzerland's Gotthard Base Tunnel, the world's longest and deepest tunnel. It runs beneath the Swiss Alps. Pictured: An Italian train at the tunnel's northern entrance on the eve of the tunnel's June opening ceremony. Length: 57 kilometers.
Lærdal Tunnel (Norway) – The world's longest road tunnel, Norway's Lærdal Tunnel has features designed to alleviate claustrophobia and tiredness. Length: 24.5 kilometers
Channel Tunnel (UK and France) – "The Channel Tunnel fundamentally changed the geography of Europe and helped to reinforce high speed rail as a viable alternative to short-haul flights,'' says Matt Sykes, tunnel expert and director at engineering firm Arup. Length: 50 kilometers
Tokyo Bay Aqua-Line (Japan) – Tokyo Bay's Aqua-Line might look like a bridge but that's because a small part of the entire structure, which comprises a 4.4-kilometer bridge and a 9.6-kilometer underwater tunnel, is visible above the water. Length: 14 kilometers total
Eisenhower Tunnel (Colorado) – Colorado's Eisenhower tunnel is one of the world's highest road tunnels, located 3,401 meters above sea level, at the highest point on the U.S. interstate highway system.
Length: 2.72 kilometers
Spiralen tunnel (Norway) – The dramatic Spiralen road tunnel in Norway, built in 1961 and comprising six spirals covering 1,649 meters, leads to one of the most spectacular viewpoints in the industrial town of Drammen.
Length: 1.65 kilometers
SMART (Malaysia) – This 9.7-kilometer SMART tunnel, the longest in Malaysia, was built to solve the problem of flash flooding in Kuala Lumpur. The tunnel has successfully controlled floods and relieved traffic congestion. Length: 9.7 kilometers
Seikan Tunnel (Japan) – The 53-kilometer Seikan is a railway tunnel in Japan with a 23-kilometer stretch that runs underwater, Before the Gotthard Base Tunnel came along, it was the world's longest and deepest rail tunnel. Length: 53 kilometers
Bund Sightseeing Tunnel (China) – A company that had worked with Disney was originally supposed to help design Shanghai's Bund Sightseeing Tunnel. Instead, a local firm created the tunnel's psychedelic lights and trippy audio-visual effects. Length: 646.7 meters