Spardo:
On arrival I find that all the warehousing is in underground tunnels.
Something like that in Derbyshire I was in some years ago, Christian Salveson was using it for wine storage amongst other things I think.
Likewise in Northwich David,in the salt mines,paperwork,files etc could keep dry as the salt provided dehumidification,there wasn’t any protection around the salt pillars that gave roof support,wondered what would happen if someone drove into one!
David