The monument at Killynan is a rath, the most common type of early medieval enclosure in Ireland, typically consisting of an earthen bank and an external fosse, or ditch, thrown up around a farmstead or small settlement. Thousands of raths survive across the Irish landscape, yet each one carries its own particular state of wear and its own small archive of subsequent land use. This one, roughly oval in plan and measuring approximately 42 metres across from northwest to southeast and 47 metres from northeast to southwest, sits quietly in working farmland, its past only legible once you know what you are looking at.

The enclosure is in poor condition. The earthen bank, which would once have formed a continuous raised perimeter, has been worn down along its northeastern to southeastern arc to little more than a scarp, a sloped edge in the ground rather than any pronounced mound. The wide, shallow fosse outside it is still traceable, though it too has softened considerably over time. More telling, perhaps, are the faint traces of cultivation ridges running across the interior from east-northeast to west-southwest. These lazy beds, as such ridges are often called, indicate that the enclosed area was at some point turned over to tillage or potato cultivation, a common fate for ringfort interiors during the post-medieval period and particularly during the pressures of the eighteenth and nineteenth centuries. A modern field fence cuts across the perimeter from west-northwest to northeast, a reminder that the working landscape has long since reorganised itself without much deference to what lay beneath.