I always thought I knew about a lot of the limerick having travelled most by-roads looking for stones and also driving around it with work.
However I never spotted this "megalithic structure" as it is described on www.archaeology.ie until i saw it on Philip Powells website.
It looks like the remains of either a cist or some part of a megalithic tomb. Locally its know as the cromlech. However even the local information board located in Glenbrohane gives very little info about it other than US Ambassador Jean Kennedy Smith visited it in 1997! Hope they took her to see a few other sites as well.