Ballycastle means town of the castle, the name derives from 1609 when the third known castle was built by the Earl of Antrim, this existed close to where the Holy Trinity Church is in the Diamond, though nothing really remains of it. An older castle existed on the cliffs overlooking the present day ferry terminal and was known as Dunineeny or Dunaneanie (Fort of the fair, games or assembly).

It was here that Sorley Boy MacDonnell of Dunluce Castle was born in 1505 and died in 1590. His brother Colla McDonnell built Kenbane Castle (kinbane, Kenban) which is two miles out of Ballycastle on the road to Ballintoy.

Ballycastle town grew from a small hamlet and important landing and slipway at the mouth of the river Margie which was originally known as Margietown, there are also references to it being called Market Town and Port Brittas. This is where the original fort would have existed, it is also where Fergus (son of Erc, King of Dariada) set out with his brothers brothers Angus and Loarn  in 502AD to expand the kingdom of Dariada into the land of the Picts.

After several battles they expanded the Dalriada kingdom to include Argyll and Bute. Fergus and his people were  known as Scotti and they gave that name to the area they conquered, this through time became known as Scotland.

It is widely written that he brought The Stone of Destiny (Lia Fiall or Jacobs Pillow) on which the Irish kings were crowned, from Tara to a new seat of power at Dunadd near the village of Kilmartin in Argyll and Bute, he became the first Irish king to rule from Scotland. Its is suggested that this Stone of Destiny which came from Tara is now in Westminster Abbey and on which the English monarchs where and are crowned.

Patricius (Saint Patrick) founded Rathmudhain (Ramoan) here in the 5th century, the old graveyard at Ramoan stands on the original site but the ruins are that of a later building. He is also believed to have fouunded a church at Carey, Culfeightrim and Drumeeny, Glenshesk as well as Armoy monastic settlement. Two local followers of his teachings, who both became saints in their own right were Gobban and Olcan (Armoy). Saint Gobban is reputed to have come from Glenshesk and been resposible for building Templastragh near Portbraddon.