Chartist Cave, Mynydd Llangynidr
These caves were used by the Tredegar Chartists to store weapons that would ultimately be used in the Newport uprising of 1839. An event which although unsuccessful was pivotal in the movement for obtaining democratic rights for all British people. Lying in the middle of a relatively featureless part of the Brecon Beacons with no paths to it marked on the map I imagine that this bit of history often remains undiscovered by walkers.