To my generation it was always called “The Dark Tunnel”, a place where you were dared to go by your pals through the blackness along a narrow slippery footpath.
By then it was an abandoned part of the canal system but in its day it was a vital link in the movement of goods and people across the country.
The story began in 1813 when the engineer Hugh Baird produced a plan for a waterway between Edinburgh and Falkirk but the proposed route upset the formidable William Forbes of Callendar House, Falkirk’s richest and most powerful landowner.
He was annoyed that the canal would pass quite close to the House and that the passengers would be able to gaze down into his private gardens.
He kicked up such a row, and enlisted the support of so many powerful friends, that the planners were forced to devise a new route which would take the canal away from the house and park.
Unfortunately the great bulk of Prospect Hill stood in the way and the only choice was to cut a tunnel 690 yards long through the solid rock.
Hugh Baird believed that the canal needed to be at least 13 feet wide with another five for the footpath and that the tunnel must be at least 18 feet from the roof to the bottom of the water.
This huge cavernous passage was to be cut through using only simple tools and primitive explosives by a very large contingent of ‘navigators’ or ‘navvies’ many of whom were recent immigrants from Ireland.
Five years after Baird first presented his plan, and with William Forbes already dead and gone, the work began.
A number of vertical pits were dug from the top of the hill down to the level of the waterway and the material lifted up using windlasses.
The ‘navvies’ then drove the tunnel back and forward to meet the next pit and so on until the passage was complete.
It is to their credit that it is a straight as a die and that the first thing you see on entering the tunnel is the light shining through the exit nearly half a mile away.
There is a famous letter sent from Falkirk to New York at the time which finishes with “a great deal of Irish men came over and is employed at it and several accidents has happened at it and two was killed by the face of the brae falling down on them . . . few of our countrymen is at it as in general they cannot stand the work”.
When the canal was completed in 1822 the trip through the gloomy passage became one of the highlights for the thousands of travellers who passed through.
Back in the 1950s the tunnel had no lights and a broken handrail and the water from the roof and the creepy light and sound made it a dare indeed.
Today there is a new handrail and lighting but it is still quite an experience.
As you walk along in the gloom spare a thought for those young men far from home whose backbreaking efforts helped create this wonder of the industrial age.