This is Falkirk Tunnel, on the Union Canal.
The original route of the Union Canal took it close to Callendar House, residence of William Forbes – and Mr Forbes did not like the idea of workmen passing so close to his residence, looking down into the gardens and upsetting him and his guests. So canal designer Hugh Baird had to find a different route – which took him right through Prospect Hill, south of Falkirk Town Centre.
And so this tunnel – 690 yards long – had to be cut with explosives and hand tools. By the time the work began on this tunnel, William Forbes had passed away, but the tunnel still was built. An army of “navigators” – or “navvies” – created this impressive tunnel.
Don’t be fooled by the photograph – this is a dark place and even the recently-installed lighting only lightens the gloom a little, as is appropriate.