Carrickabraghy Castle (Irish: Caisleán Charraig Bhrachaí stands in the townland of Carrickabraghy meaning "Friars Rock" in Irish) on a rocky outcrop at the north-western extremity of the Isle of Doagh, at the head of Pollan Bay, in the north of Inishowen, a peninsula on the north coast of County Donegal, Ireland.

It is thought the word could be a personal name, as it is mentioned in the pre-Norman genealogy of the Cineal Fhearghasa, and could be an ancestor of the McFall sept. Machtochair, in his book Inishowen, Its History, Traditions and Antiquities says Carraig Bhrachai means 'The Friars Rock'.

The earliest historical mention of Carrickabraghy comes in The Annals of the Four Masters; In 834 The monarch Niall Caille led an army into Leinster; one of his officers, Fearghas, son of Badhbhchadh, lord of Carraig Bhrachai, was killed by Munstermen.

The Ulidians entered their unguarded camp by night and killed a number, among whom was the king of Carraig Bhrachai, Sitric O Maolfabhail.

In 1166 Aodh O Maolfabhail, king of Carraig Bhrachai, was treacherously killed by Muireartach, son of Niall Mac Lochlainn.

Seán Beattie, in his book Ancient Monuments of Inishowen, recounts a tale regarding a Viking raid on Donegal in the tenth century.

There was good reason for this as The Isle of Doagh was unfamiliar territory to the English and was easily defended as it was only accessible at low tide.

The natural choice, his first-born son, Cathaoir Rua, had not yet come of age, and there were other forces at work wanting their own man installed.

Aodh Rua O Donaill, the Lord of Tir Chonaill, wanted an experienced and mature man at the helm, someone who would remain loyal to him, effectively keeping the peninsula and its resources under his control.

The English commander in Derry, Sir Henry Dowcra, was not bothered who the successor was as long as they were ready to submit himself and the territory to the Queen.

Aodh Bui Mac Daibheid, though cunning negotiations with both Dowcra and O Donaill, had Cathaoir Rua O Dochartaigh rightfully installed as Lord of Inishowen in May 1601.

The English became suspicious the Earls would return with forces from Spain to reclaim their lands, and thought Cathaoir Rua had a part to play in this plan.

A grant from the National Rural Development LEADER Programme and over €30,000 from local fundraising events and contributions from supporters allowed the first phase of the work of conservation to be completed in December 2013.