Tunnel
From Conservapedia
A tunnel is a passageway through or under an obstruction, like a mountain.
The Gotthard Base Tunnel is the world's longest tunnel with 57 kilometers (around 35 miles) through the Swiss Alps, completed after 6 decades of work in 2010,[1] and opened on the first of June 2016, and in full service on 11 December 2016.[2]
Until then the longest tunnel in operation was Japan's Seikan Tunnel.
