The site measures between 16.5 and 20 metres in internal diameter, though centuries of weathering and agricultural activity have left it in poor condition. The defensive perimeter, which would have originally formed a substantial stone wall, now appears as little more than a scattered line of stones tracing a rough circle across the landscape.

The fort makes clever use of the natural topography, incorporating a rocky outcrop into its northern boundary; a common feature in cashels where builders would integrate natural defensive features into their constructions. This outcrop creates a dramatic two-metre drop on the western side whilst remaining level with the surrounding field to the east. The site occupies what archaeologists describe as “good land”, sloping gently northwest towards a small stream, indicating that despite its defensive purpose, the fort’s inhabitants chose their location with agricultural potential in mind.

This particular site was documented during the comprehensive Archaeological Survey of County Donegal, conducted in 1983 by Brian Lacey and his team of researchers. Their work catalogued field antiquities spanning from the Mesolithic period through to the 17th century, creating an invaluable record of Donegal’s archaeological heritage. Ringforts like this one at Dunwiley served as the homes of prosperous farmers during the early medieval period, typically dating from around 500 to 1200 AD, and represent one of the most numerous archaeological monument types found across the Irish countryside.