This ringfort, or cashel, measures approximately 20.7 metres across its interior, though only the faintest traces of its southwestern half remain visible today. Where defensive walls once stood, visitors can make out slight remnants of a grassed-over structure, roughly 1.65 metres wide, that would have encircled and protected the settlement within.

The interior of the cashel remains remarkably flat, suggesting it was carefully levelled when first constructed, likely during the early medieval period when such fortified homesteads dotted the Irish countryside. These ringforts served as defended farmsteads for prosperous families, offering protection for both people and livestock whilst providing a clear statement of status in the landscape. The fair pasture that surrounds Caiseal Charna today hints at why this location was chosen; good grazing land would have been as valuable to its original inhabitants as the strategic view across the river valley.

Though time and weather have worn away much of this ancient structure, what remains offers a tangible connection to Donegal’s medieval past. The site was documented as part of the comprehensive Archaeological Survey of County Donegal, conducted by Brian Lacey and his team in 1983, which catalogued field antiquities from the Mesolithic period through to the 17th century. Even in its diminished state, Caiseal Charna stands as a reminder of the thousands of similar settlements that once formed the backbone of rural Irish society, each one a small fortress in a landscape shaped by centuries of habitation.