This could be Cornwall ...

but actually it is deepest Derbyshire.
In the very heart of the White Peak District is Magpie Mine a very significant lead mine. The actual shaft is over 200 metres deep and quite a few ruins remain from its working heyday.
I had heard of Magpie and seen many pictures of it but I had never been there. Quite a nice sky makes for a lovely backdrop but there is an amazing potential for pictures on future visits.