It was never discovered by walking the land or reading an old map. It came to light through LiDAR, a remote-sensing technology that fires pulses of laser light from an aircraft and measures the returns to build precise elevation models of the ground surface. The data strips away vegetation and reveals subtle earthworks that centuries of farming have reduced almost to nothing.

The site was first identified by Susan Curran as part of an M.A. thesis with University College Dublin, working from a LiDAR dataset commissioned by Leitrim County Council and the National Roads Authority. What the data showed was a subrectangular or D-shaped enclosure sitting on a rise of a north-east-facing slope, measuring roughly 40 metres on its north-west to south-east axis and 32 metres across. A ringfort, or rath, is a type of enclosed farmstead built predominantly during the early medieval period in Ireland, roughly the fifth to twelfth centuries, typically defined by one or more earthen banks and ditches encircling a domestic area. At Cloonteem, the defining feature is a slight scarp, a low step in the ground, widening to about 3.2 metres and reaching 0.4 metres in height at the south-east, and growing more pronounced as it curves from north around to the south-west. There is no visible fosse, the ditch that usually accompanies a rath's bank, and no identifiable entrance survives. A sunken field drain has truncated the western perimeter, and further drainage work may have cut across the interior.

What makes the Cloonteem example quietly instructive is how ordinary its survival story is. Improved pasture, modern drainage, and centuries of agricultural use have flattened it to near-invisibility at ground level. It is the kind of site that reminds us how much of the early medieval landscape persists beneath Irish fields, registered now only when the light, or the technology, falls at exactly the right angle.