The coincidence of two quite different periods of Irish land use, each occupying exactly the same commanding hilltop, gives this site an oddly layered quality that most raths, as these early medieval enclosures are commonly known, do not possess.

A rath is an earthen ringfort, the most common monument type in the Irish landscape, typically interpreted as the enclosed farmstead of a prosperous family during the early medieval period, roughly the fifth to twelfth centuries. This example on Windmill Hill sits within a small deciduous plantation and is unusually well-defended by three concentric earthen banks separated by intervening fosses, the ditches cut between the banks to deepen the obstacle. The innermost bank stands about a metre high on its outer face, with a formal entrance gap of just over six metres facing south-east. The middle bank, standing slightly higher at 1.2 metres, has been partially absorbed into the later field fence system to the north-west and south-west, as often happens when old earthworks are repurposed by farmers working the same ground centuries later. A low curving bank appears to block what was once the entrance on the south-east side of this middle circuit, and may represent a later modification to the original layout. The outermost bank survives only partially, as a low rise traceable from the north-west around to the east-south-east. The interior itself is gently domed, rising slightly at the centre before sloping down toward the inner bank, and it is at that highest central point that the ruined windmill now stands, a post-medieval structure making use of precisely the elevation that made the site worth enclosing in the first place.