Known locally as the ringfort at An Bhinn Dubh, this circular mound rises between one and 1.6 metres above the surrounding field, with a diameter spanning nearly 19 metres. Early Ordnance Survey maps from the 19th century marked the site simply as 'Fort', whilst later editions depicted it as an oval feature with distinctive hachured markings, suggesting its importance to early cartographers who recognised it as something worth recording.

The structure itself bears the scars of time and human interference; its northeastern section has been quarried away, leaving the once complete circle permanently damaged. This type of earthwork, commonly called a rath or ringfort, represents one of Ireland's most widespread archaeological features, typically dating from the early medieval period between roughly 500 and 1200 CE. These circular enclosures, defined by earthen banks and external ditches, served as fortified homesteads for farming families, providing both protection and a statement of status in the landscape.

The waterlogged terrain surrounding this particular fort may have offered strategic advantages to its original inhabitants, with the marshy ground providing natural defence whilst the nearby River Reelan supplied water and transport routes. The Archaeological Survey of County Donegal, compiled in 1983, documented this site amongst hundreds of similar monuments scattered across the county, each one a tangible link to the generations who shaped this landscape long before modern field boundaries and roads carved up the countryside.