The men and women who built this engineering marvel recall what is was like to work in such a challenging environment and the hurdles that the project faced.
The pace hots up as the British and French tunnellers race towards the breakthrough point, which occurs on December 1, 1990 when the two sides meet. By 1994, the tunnel was open for business, but in 1996 a catastrophic fire highlighted the dangers of operating a railway tunnel that is 31 miles long.