This ancient fortification consists of three distinct features: an inner earthen bank, a defensive ditch called a fosse, and an outer bank that together create a protective ring around what was once a farmstead. Today, the banks have been worn down by centuries of weather and neglect, whilst the fosse has filled with silt and become overgrown with rushes, giving the site a rather melancholic appearance.

The ringfort at Rathglass represents one of thousands of similar structures scattered across the Irish landscape, most dating from the early medieval period between roughly 500 and 1100 CE. These weren't military fortifications in the traditional sense; rather, they served as defended homesteads for prosperous farmers and their families. The circular enclosure would have contained a dwelling house, perhaps built of wattle and daub or timber, along with various outbuildings for livestock and storage. The defensive banks and ditch offered protection from cattle raiders and wild animals whilst also serving as a clear statement of status and land ownership.

What makes this particular site intriguing is its placement on level but waterlogged ground, surrounded by what archaeologists note is good quality land. This suggests the original inhabitants deliberately chose this spot despite the wet conditions, possibly for defensive advantages or proximity to the river for water and transport. A low, disused field fence now cuts through the interior of the ringfort, a reminder that this ancient home has long since been absorbed into the agricultural landscape of modern Donegal, its original purpose fading into local memory and archaeological record.