Dorothea was a large slate quarry, with the slate mined in huge pits due to the direction of the seams, so it’s now a popular destination for divers – there’s still a lot to see on the surface, however.
Nearby was a country house that became over-run by the quarry – the site is very confusing with trackways and railways running over and under each other, and trees growing up and through buildings. Very atmospheric.
It wasn’t all surface, though – this tunnel was interesting to get to, but worth a visit:
Back on the surface, there are some gigantic slate piers, used to haul blondins (cable-winched wagons) up from the quarry.
Finally, we stopped off at the beam engine – it’s in a bad way, but at least it’s very well sealed up at the moment. We met the keyholder on the way out – who sounded amenable to letting people look around if he was there.