With an internal diameter of approximately 27 metres, this circular fortification now exists mainly as a reconstructed field boundary, its original earthen banks and stone walls having largely collapsed over the centuries. Earlier surveys from the 1940s paint a more complete picture: a level circular space surrounded by an earth-covered stone wall with an entrance opening to the southwest, typical of these early medieval defensive structures that dotted the Irish countryside.

The site has yielded intriguing glimpses into its past through various discoveries. A large recumbent stone bearing cupmarks was found just outside the southern perimeter, whilst excavations at the centre revealed what appeared to be part of a souterrain, one of those mysterious underground passages often associated with ringforts. Local folklore from 1946 held that a 'Dane' (likely referring to a Viking) was buried within the enclosure, and that the cashel connected to another souterrain some distance to the southwest. These tales of Viking connections proved rather prescient when, in 1966, workers dismantling parts of the site uncovered a cache of four silver Viking bracelets hidden within the cashel's wall, artefacts that speak to either trade connections or perhaps a more direct Norse presence at this Donegal stronghold.

Today, visitors to Roosky will find only subtle traces of this once-substantial fortification, its stones long since repurposed for field walls and its earthworks weathered by centuries of farming. Yet the site remains a testament to the complex layers of Irish history; from its likely origins as an early medieval Irish ringfort to its possible Viking associations; all compressed into this quietly significant spot in the Donegal landscape.