Are you referring to Grimes Graves by any chance Bill?
When we first came up here in the 70's, you could go down into the workings, and crawl along the tunnels.............
The PC/HSE brigade have done for that......all fenced off, can't get within 25 yards (sorry, meters, or is it metre's) of the opening now......I think they've done the same with stonehenge
It'll be stabilisers on motorbikes soon, mark my words!