Coolnalong Castle is a 17th century Elizabethan fortified mansion similar to Coppinger's Court in Rosscarbery. Also on this site is Durrus Court which was one of Lord Bandon's houses.
External Links:
https://www.geograph.ie/photo/3716213
https://durrushistory.com//?s=coolnalong&search=Go

A New Type Of House

By Francis Humphreys, Durrus: A Parish History.

The Old Court was a building of considerable historical significance. It was built between 1610-1640, that is after the Battle of Kinsale and before the 1641 rebellion, by Teige na Muclach of the McCarthys. It was built in the traditional Irish-Jacobean style of which Coppingers Court near Rosscarbery is a prime example. There is extensive correspondence in the Paddy O'Keeffe papers (in the Cork Archives), a well-known local historian, describing his attempts to have Cul na Long taken over by the Monuments Commission and thus preserved for posterity.

It's importance, as he describes it, was that it was built by craftsmen of a tradition, who knew of no other kind of Big House except the castle or the monastery and so transferred the castle-monastic ornamentation to the new house type. The previous McCarthy residence had been nearby Rossmore Castle, a much simpler building. The Monuments Commission rejected the application and both building continue to decay.