Grime's Graves - Prehistoric Flint Mine 
“Grime’s Graves is a unique visitor attraction in Norfolk as the only Neolithic flint mine open to visitors in Britain.…” – official site
Ease by public transport:
Unknown
“Grime’s Graves is a unique visitor attraction in Norfolk as the only Neolithic flint mine open to visitors in Britain.…” – official site
Ease by public transport:
Unknown