The bank still rises to a considerable height on its outer face, around two and a half metres, though from the interior the climb is noticeably less dramatic at just over a metre. That difference is a clue to how these structures were built: earth was dug from a surrounding fosse, a circular ditch, and piled inward to form the enclosing bank. Here, though, the fosse is gone. Centuries of ploughing have levelled it, leaving the bank stranded in pasture without its counterpart, like a frame with the picture removed.

Ringforts, also called raths, were the most common form of enclosed settlement in early medieval Ireland, typically dating from roughly the fifth to the twelfth century. They served as farmsteads rather than military fortifications, the bank and ditch providing a degree of security for livestock and household alike. The Coolbane example is roughly circular in plan, measuring about 35.7 metres north to south and 38.3 metres east to west, dimensions fairly typical of the single-bank variety. The interior is level, which often indicates that whatever structures once occupied the space, whether timber houses, animal pens, or storage buildings, have long since vanished into the soil. Around 140 metres to the east, a second enclosure once stood, though it has since been levelled entirely, leaving the ridge-top rath as the more legible of the two.