A large rock, named the Friars Rock in the Isle of Doagh in County Donegal, stands the ruin of Carraickabraghy Castle. The translation of the Irish name into English is Castlebrack.
Between the 9th and 13th century Inishowen was divided into three sectors, Aileach, Bredach and Carraic Brachaidhe (Carraickabraghy) which is situated in the west of Inishowen.
The castle was last inhabited in 1665. The structure of the castle included an oval bawn and towers seven circular towers. The bawn and towers enclosed a keep. To the south of the keep stood a small tower which is believed to have belonged to a church. The walls of the castle are 3 ft 9 inches wide. To the south of the bawn an abundance of sandhills now exist.