This ancient earthwork occupied a patch of marshy, heather-grown land at An Ailt Leathan, though you won't find any trace of it marked on the first edition Ordnance Survey six-inch maps. The site's absence from these detailed Victorian-era surveys suggests it may have already been in a state of decay or considered too insignificant to record when cartographers first systematically mapped Ireland in the 19th century.

The enclosure represents just one of countless archaeological features scattered across County Donegal's rugged terrain, bearing witness to thousands of years of human activity in this northwestern corner of Ireland. Single-ringed enclosures like this one typically date from the early medieval period, roughly between the 5th and 12th centuries AD, and would have served various purposes; some functioned as defended farmsteads, others as livestock enclosures, and occasionally as ceremonial spaces. The marshy conditions around the River Finn may have actually helped preserve whatever remains lie beneath the heather, though the site's current state remains largely unknown.

This information comes from the comprehensive Archaeological Survey of County Donegal, compiled by Brian Lacey and his team in 1983, which catalogued field antiquities spanning from the Mesolithic period through to the 17th century. The survey represents a monumental effort to document Donegal's archaeological heritage, recording sites that might otherwise be forgotten as the landscape continues to change through farming, development, and the simple passage of time.