Harford Hills is an underground chalk quarry that was in operation until a few decades ago. The tunnels near the current entrance have soot stained roofs presumably from old candles and lamps. Other sections don’t have this – one report on another website thought those were more recent, from a time when workers used battery powered lamps.
There are a few loops I found out later (I’d printed off a map but then left it at home
) which probably explains why I took quite a few photos of one particular tunnel several times over a couple of hours. That might also account for the feeling that this was a huge system of tunnels.
A copy of that very same useful map is at the bottom of this page
http://www.geograph.org.uk/article/Harford-Hills-Chalk-Mines
Soot staining near the entrance
Get the feeling I'm going the wrong way
Handy jacket left behind by the miners
There are a few loops I found out later (I’d printed off a map but then left it at home

A copy of that very same useful map is at the bottom of this page
http://www.geograph.org.uk/article/Harford-Hills-Chalk-Mines
Soot staining near the entrance
Get the feeling I'm going the wrong way
Handy jacket left behind by the miners