The massive castle, which looks even larger because of its picturesque situation on the edge of a cliff, was supposedly built in 1446 by Cormac MacCarthy "the Strong", probably on the site of a castle occupied by the Lombards, whom the MacCarthys had displaced. It has an L-shaped plan with five storeys, the lower two being under a pointed vault with walls 12 feet thick; higher up the walls get thinner and the rooms bigger. The building sequence is a little puzzling, but the slender tower containing the main stair and a tier of small rooms evidently predates the main block. The whole is crowned with high stepped battlements, projecting more than 2 feet beyond the walls and carried by long inverted pyramid corbels.

The MacCarthys held onto the castle with a few interruptions until the Williamite wars, when Donagh MacCarthy, the fourth Earl of Clancarty, supported the losing side and had his estates forfeited. It is said that before leaving he cast the family silver into the lake. The property was acquired by Sir John Jefferys, who built a Gothic-style house onto the castle with pointed windows and curvilinear pinnacled battements. This was burnt c. 1820, but a semi circular staircase tower still remains. Nearby the family made a megalithic garden folly and in 1874 they built a Scottish Baronial-style house overlooking the lake in the park.