The brick tunnel will be a Victoria sewer (probably in London), the mine photos (most of them) are from Box mine near Bristol, and the last one looks remarkably like a viaduct in Brighton.
The CPF UK meet went to Box last year, this is a summarised set of photos:
Taking a group of CPFers into a mine, lighting was not a concern!!
Some of the motley crew getting ready to go.
The way in turned out to the be easiest of the entrances.
Nice to see the ceilings looking stable and safe to walk under.
Some of the miner's artwork.
An underground crane.
These tunnels are all hand cut.
We thought we would take one of the smaller blocks with us – "You take that end!"
After coming through a crawl space it got much more spacious.
Another one of those safe ceiling being held up while we all got through.
A lunch break.
Welcome to the Cathedral.
Light stick… that's not a light stick.
The quantity of material cut and removed by hand is astounding.
It looks quite a strong ceiling support, but the wood is now as strong as a wet paper bag.
Having to crawl through a small hole in the wall.
A nuclear bunker door just before the light sabre broke through.
Who put that door there?
Some slightly more modern ceiling support.
The remains of a WW2 wire mesh barrier. Looks like a great deal more effort went into making this than it took to get through it.
The miners used to come to work down this ladder.
Then down the steps.
One of the saws used to cut out most of these tunnels.
A crab-winch (I think).
A nicely built tunnel looking slightly out of place.
The way out was a much smaller opening you needed to wriggle through like a worm – glad to be out!