Answer:
The longest train tunnel is in Switzerland.
Step-by-step explanation:
The longest train tunnel is located in Switzerland. It came into operation after almost two decades of construction work. It is 57 kilometers long which is equal to 35 miles. It is also the deepest rail tunnel in the world. It is called the Gotthard Base Tunnel. This tunnel is constructed between the beautiful and mesmerizing views of Switzerland. Switzerland is famous for its beautiful landscapes among tourists.