Man-made underground passage (Site of)

Yes. West Cork still keeps a buried chamber inside a ringfort, marked only as a cave on old maps and perhaps hidden beneath two clumps of nettles. People may have cut the passage for storage, ritual or escape, while others avoided it because darkness and forgetfulness make such places dangerous. The chamber no longer answers to a name, but it still waits beneath the grass for someone willing to look where the land stopped speaking.