Try and see these on tours of Ireland if only for the sheer age of the things.
Dolmens are Stone Age megalithic tombs.
They consist of between three and seven uprights carrying a capstone weighing up to one hundred tons.
A good example is at Browneshill , County Carlow.
These massive structures were probably erected by means of a removable ramp. Clever for the time.
Poulnabrone Dolmen in County Clare has been radiocarbon-dated to 3800 to 3200 BC. Yes "before Christ" !! It houses some twenty-two burials.
So if on Ireland tours please dont think of the Dolmens as "hidden gems"....think of them as "must see" attractions.