The outer bank reaches nearly four metres at its highest point, which is considerable for a site sitting quietly in rough grazing land, unremarked by passing traffic and largely unknown outside specialist circles. What makes it quietly arresting is the combination of scale and completeness: two banks separated by a fosse, the ditch between them, with a causewayed entrance still discernible on the south-west side, oriented, perhaps deliberately, towards the slope and the river below.

This is a rath, the earthwork variant of the ringfort, a type of enclosed farmstead built throughout Ireland during the early medieval period, roughly between the fifth and twelfth centuries. Thousands of them survive across the country in various states of preservation, but this example at Kilmartin retains its double-bank arrangement, which would have signalled something about the status or resources of whoever occupied it. More unusual still is the presence of a souterrain in the interior. A souterrain is an underground stone-built passage or chamber, typically associated with ringforts, and thought to have served for storage, refuge, or both. Their construction required significant labour and some degree of planning, and their survival alongside intact earthworks makes a site like this a relatively coherent picture of early medieval rural life in the Cork landscape.