The Gotthard Base Tunnel has just been completed and it is 35 miles long. Train travellers can now travel from Zurich to Milan by going underneath the Alps instead of over them and it will only take them 2.5 hours.
The journey through the tube
Construction began back in 1996 with the intention of making it easier for regular passengers as well as freight to traverse Europe's most populated stretch.
Business Insider stated that it cost Switzerland $10.3 billion (£6.6 billion) and saw more than 28 million tons of earth excavated.
The record for the longest tunnel was previously held by the Seikan Tunnel in Japan which was only 14.5 miles long.
A video was posted last year by Siemens which gives some extra details on the Gotthard Base Tunnel.