This circular stone enclosure, measuring approximately 25 metres across, occupies a south-facing slope amongst rocky terrain, poor pasture and bogland. Though time has taken its toll on the structure, its ruined walls still trace a clear circle across the landscape, with modern field walls now incorporated into the southern section where the original stones once stood.

The interior of the cashel reveals an interesting topography that would have influenced how its inhabitants used the space. The northern portion remains relatively flat, providing what would have been the most practical area for dwellings or daily activities. Moving southward, the ground begins to slope noticeably, and about five metres from the southern wall, a natural ledge of rock cuts across the site from east to west, rising two metres in height. This natural feature would have created distinct zones within the enclosure, possibly separating living areas from spaces used for livestock or storage.

Cashels like this one were typical defensive homesteads in early medieval Ireland, usually dating from roughly 500 to 1200 CE. Built with drystone walls, these circular fortifications housed extended families and their livestock, offering protection in an era when cattle raiding was commonplace. The Grogagh cashel's position on marginal land suggests it may have been home to a farming family of modest means, making use of whatever grazing the rocky slopes and bogland could provide. Today, it forms part of Donegal's rich archaeological landscape, documented in the county's comprehensive archaeological survey compiled by Brian Lacey and his team in 1983.