This cairn stands on top of Castlegale hillfort. The Ballyhoura Hills project refers to it that “it is possible that it was a prehistoric burial cairn, given the spread of stone strewn around the hilltop and the occurrence of similar cairns in locations such as Carntigherna and on the Galty Mountains.”
It is also meant to be the remains of a tower built by the Castle Oliver estate and when the owners of the estate reputedly flew a flag from the tower when in residence.
Id follow what the Ballyhoura project says, that it is likely to have been a reused prehistoric cairn.