The River Clare runs to the south, and it is easy to imagine why someone, many centuries ago, chose this particular knoll as a place to build and be seen from, without being easily rushed.

The ringfort at Lack is a subcircular earthwork measuring roughly 38 metres across on its northwest-to-southeast axis. It survives in fair condition, defined by two banks with a fosse, or ditch, running between them, a defensive arrangement typical of the raths built throughout Ireland during the early medieval period, roughly the fifth to twelfth centuries. What lifts this example slightly out of the ordinary is that the inner bank is faced with stone, suggesting a degree of investment and permanence by whoever occupied the site. A later field bank has since been constructed across part of the monument, running from the north-northwest around to the southeast, cutting over the fosse and outer bank and effectively absorbing a section of the original earthwork into the working landscape of a later age. Beneath the interior of the enclosure there is also a souterrain, an underground stone-lined passage or chamber that would have served the original inhabitants as a place of storage or refuge, and perhaps both.