More mines and found dungeons

I like the idea of 'found' dungeons and incorporating accurate geology in dungeons/underground works

Over at io9.com, a pictorial of several historic mines.  Some closed, some still active, most open to tourists.  But they may provide some inspiration and fodder to those great underground temples and passageways for your delving needs...

Of the list, I've been to the Wieliczka Salt Mine, outside of Krakow, Poland.  Although it was first built in the 13th Century, local salt mining extends back to the Iron Age, and was a significant driver in Poland's place as a regional economic power.  Descending into a mine that was active for seven centuries is quite intimidating.

I think this is most parties' henchman tally.