What makes it curious is not dramatic scale but the way the landscape has absorbed and partially overwritten it: a modern field boundary has been laid directly over the north-western to eastern arc of the original enclosing element, effectively replacing one boundary with another across roughly a thousand years of land use.

A rath, as ringforts built from earth rather than stone are commonly known, was the typical farmstead of early medieval Ireland, generally dating from somewhere between the fifth and twelfth centuries. They consist of a circular area enclosed by one or more earthen banks and ditches, and were once so numerous that several hundred thousand may have existed across the island. The Killeline example is modest in scale: the enclosed area measures roughly 27.8 metres north to south and 26.7 metres east to west. The enclosing earthwork survives in two forms. Along the western to north-western arc, an earthen bank rises about 0.3 metres on its interior face and 1.15 metres on its exterior. Along the eastern to north-western arc, the boundary takes the form of a scarped edge, meaning the ground has been deliberately cut to create a steep profile, measuring 1.15 metres high and 3.2 metres wide, with a shallow external fosse, or ditch, roughly 0.25 metres deep and 1.8 metres across. The survey was compiled by Denis Power and uploaded to the national record in August 2011.

The fort sits on a slight south-facing slope and the interior is level, though currently waterlogged and under marshy pasture, which limits what can be seen underfoot. The most legible parts of the earthwork are the western bank and the scarped section to the east, where the change in ground level is still perceptible from a field-level vantage point. The overlying field boundary to the north-west complicates the circuit but also, in its own way, marks how continuously this particular patch of ground has been used to divide space and define ownership. Visiting in drier summer months would make the ground easier to read, though the marshy interior may persist regardless of season.