The Department of Transport said a sale will only be made to "a public body" able to take on the maintenance of the mile-long tunnel.

BBC: Harecastle tunnel offered for sale by the government

The two species of mice were successively bred, and those hybrids built long, two-tunnel burrows like oilfield mice - showing that the behaviour is a "dominant" trait.

BBC: Mouse burrowing 'in their genes'

Moreover, dual U.S. and Canadian approval, inhospitable terrain, environmental concerns, long-term financing and tunnel administration will need to be adequately addressed.

CENTERFORSECURITYPOLICY: The Bering Strait Tunnel Project

The deadliest tunnel-fire incidents happened in 2001 in the 16.9 kilometer-long (10.5 miles) Gotthard tunnel when a crash involving two trucks caused a fire in the tunnel, killing 11 people.

WSJ: Police Say 28 Dead in Swiss Bus Crash

The 1.7 mile-long (2.7km) Butterley tunnel, which carried the Cromford canal, was opened in 1794 and closed in 1900 after a partial collapse.

BBC: Butterley tunnel gets Scheduled Ancient Monument status

Rick Suhr has connected two steel Quonset huts, one with a long, narrow tunnel measuring 100 feet for the run-up.

WSJ: Suhr relishes breaking indoor pole vault mark

This can ensure you are building a correct standing workplace and not doing anything to harm yourself or create long-term arm, shoulder, or other joint problems (or carpal tunnel syndrome).

FORBES: Connect

The Brooklyn-Battery Tunnel links Manhattan with the borough of Brooklyn, which is on Long Island.

BBC: Sandy: Storm-hit New York declared major disaster area

The twin-bore Sasago tunnel is an estimated 4.3km (2.7 miles) long and is on one of the major highways out of Tokyo.

BBC: Japan Sasago tunnel: Collapse traps cars

First conceived nearly one-hundred years ago during the reign of Russian Tsar Nicolas II, the BST would be the longest tunnel in the world - over twice the length of Europe's 30 mile long "Chunnel" linking Britain and France.

CENTERFORSECURITYPOLICY: The Bering Strait Tunnel Project