Yet another Dublin curiosity, I'd never heard of this until I stumbled upon it here: http://www.irishstones.org/place.aspx?p=246 And what a nice surprise it is, nestled to the side of an, until recently, overgrown graveyard.
I arrived and didn't hold out much hope of getting to the stone as the walls of the church/graveyard are very high and the gate seemed forbidding. However, there was a groundsman there and I pushed through the gate no problem. I asked him if he knew of the stone and sure enough he led me to it. I asked if he knew much about it and he said he had heard that the tradition was to pass a newborn through the hole in a cleansing ritual, similar to baptism I guess.
The man was very friendly and showed me around the grounds – turns out that he's a volunteer, doing the work to keep busy and doing a fine job, having cleared what was a seriously overgrown perimeter.
The stone, not even a metre square, sits there amongst the various relics of Christianity, a reminder of our pagan past, a survivor, pitted and pockmarked and tilting and still here, a small trace, or testament, to a tradition that remains despite all that time has altered.