A rath is an early medieval enclosed settlement, typically a circular earthen bank and ditch protecting a farmstead or the home of a person of local standing. At Cooleagh, that enclosure was nearly fifty metres across, which places it at the larger end of the ordinary domestic scale, and the surviving south-west quadrant preserves the original proportions almost intact: a bank nearly two and a half metres high on its outer face, with a fosse, or external ditch, cut to a depth of over a metre beside it.

The rest of the circuit has been levelled over time, reduced to a barely perceptible rise across the grass, less than a metre high and spread across four metres of ground. Aerial photography from around the 1970s, recorded under the reference CUCAP AYO 80, captured the monument at a moment when the full enclosing bank was still traceable and the site was thickly overgrown with scrub, the surrounding field similarly rough. Since then, the land has been brought back into pasture, which has clarified the surviving earthwork but erased whatever remained of the rest. The ringfort sits on a gentle east-facing slope with a river passing close by to the east and south-east, a typical placement: early farmers chose well-drained ground near water, and the landscape here, gently undulating and now fully reclaimed, would have suited exactly that kind of long-term occupation. What remains has been absorbed into a field boundary, which is part of the reason the south-west quadrant survived at all; the bank was useful, so it was left.