I was in (I think it's) Ma Boyles Inn by the Sailors Church. The pub's then landlord told me that underneath were the dungeons which at one time housed French POWs from the Napoleonic era. He said everything was just as it was when it was closed. The shelves upon which they slept, their grafitti on the walls, eating utensils, tables; the lot.
He added that there were tunnels underneath through which one could walk at least to the Pig and Whistle pub.
It seemed to add up because I think it was there, that beautiful white building facing the Strand, where Liverpool's original castle or fort stood.
I asked why it wasn't 'opened' as a tourist attraction. It was a money spinner. He said because of its connotations to the slave trade it would be politically incorrect. Just repeating what he told me. Don't shoot the messenger.