Ballyaghagan

Ballyaghagan - the rath close to the Hightown Road carpark for Cavehill Country Park is alluded to in the Irish Itinerary of Fr Edmund McCana who travelled in the area in 1643 or rather in the notes appended to the Rev W. Reeves's translation of that document from the latin.
Rev Reeves notes : "Balliston, or Ballyvaston, near the Hightown Road, on the confines of the townlands of Ballyaghagan and Ballyvaston, at a place called Whurr's Pound. The traces of the chapel are observable in the nearly obliterated circle of a rath".
The Rev Reeves was writing in the early 1850's and is quoted in the Ulster Journal of Archaeology vol 2 Series 1 p 58.
I have heard people talking of there being an unidentified building in the rath area of much later date than the rath complex. Perhaps this is the chapel remains?