A lot of visitors to Chesterfield will never know what is hidden underneath their feet - an abandoned underground railway tunnel.
Explorer Patrick Dickinson who has also explored Haddon Hall's forgotten railway visited the Chesterfield tunnel which reportedly has not been used since the 1960's and runsparallel to Rother Way.
The tunnel which is 'prone to flooding' and is very muddy is 494 yards in length - but use to be longer.
Constructed in the 1890's it formed part of the Chesterfield Loop.
Patrick said: "You get a feeling of how big it is.
"It was not easy to film at all.
"There was orange mud everywhere - it stains your boots and clothing.
"You can 70 years of soot caked in the ceiling.
"It's surprising how much fun you can have down here with a camera."
The video has more than 66,000 views on Youtube.