The lands of Ballyness were originally granted to Henry Hart in 1611, who quickly sold them to Wybrant Olphert, a Dutch Protestant settler. By 1619, records describe ‘a stone fort, and house in it’ occupied by an English family, though just three years later Olphert, then living in Derry, reported that he had only partially repaired the ‘old bawn’, which otherwise ‘lyeth waste’.

Today, what remains of this small polygonal bawn tells a story of defensive architecture adapted to challenging terrain. The ivy-covered north wall, standing just over three metres at its highest point, contains the original entrance; a lintelled doorway that still preserves its draw-bar hole and socket, features that would have secured the fort against unwanted visitors. Behind the doorway lies an intriguing hall-like space with walls reaching 2.5 metres high, accessed by stone steps built into the thickness of the wall itself. Archaeological evidence suggests this north wall may have formed part of a house within the bawn, though no clear traces of internal structures survive. The eastern wall shows signs of careful construction with a slight batter, or outward slope, to its exterior face for added stability, whilst the southern and southwestern corners exist only as foundation courses.

The fort’s strategic position wasn’t just defensive; immediately north of Castle Bawne, the land has been carved to accommodate two mill races, showing how subsequent generations adapted the site for industry. Though much of the western extent has vanished and the lower facing of the north wall has crumbled away, these ruins offer a tangible connection to the complex history of plantation-era Donegal, when Dutch, English and Scottish settlers attempted to establish themselves on lands that had been Irish for millennia.