I climbed up from the road, best to use http://mountainviews.ie for directions. The cairn isnt that obvious from the surrounding hill side when you are right beside it however it can be seen from far away. The north side of the cairn really isnt cairn like at all and it seems to be the east-south-west sides that are cairn like.
If it is a proper cairn then it is pretty huge, i couldnt really estimate because the north side flattens off.
You can see for miles up here and to a number of different hill-tops, some have cairns that are marked on the map, others that dont but have cairn-like features on top.