I am Very Reliably (and kindly) Informed that it is Grangebeg to which the news above refers.
The 'Survey of Megalithic Tombs of Ireland Volume III' says that there are - or were - five or six blocks here, from 1 to 3m long. One was upright, another rested against it, and three more lay on the ground. According to Comerford's "The Dioceses of Kildare and Leighlin" (1883), II, 239, a human skeleton was found here.
But it's not clear what kind of structure this is. It has been called a dolmen, but that's by no means certain. In fact, the Survey says "it may be largely natural."
Of course it could actually be a "Druid's Altar" as that's what it's been called on OS maps in the past.