The Gotthard Base Tunnel is a railway tunnel in Switzerland that is the longest and deepest in the world. It runs for 57 km (35.4 mi) between Erstfeld in the canton of Uri and Bodio in the canton of Ticino. The tunnel
From Wikipedia
The Gotthard Base Tunnel is a railway tunnel through the Alps in Switzerland. It opened in June 2016 and full service began the following December. With a route length of 57.09 km (35.47 mi), it is the world's longest railway and deepest traffic tunnel and the first flat, low-level route through the Alps. Located at the heart of the Gotthard axis, it is the third tunnel to connect the cantons of Uri and Ticino, after the Gotthard Tunnel and the Gotthard Road Tunnel.