What makes Lisnacush worth a second look is the layering: an early medieval rath, a probable seventeenth-century house built inside its banks, and a large artificial pond that may have served that later household, all occupying the same modest patch of ground.

The rath itself, a type of enclosed farmstead built during the early medieval period, typically by a single family of some local standing, measures 57.5 metres in diameter. It is defined by a broad earthen and stone bank up to 1.3 metres high and nearly ten metres wide, with a shallow external fosse, that is, a ditch dug to reinforce the enclosure, running around the outside. At the south-south-east, a three-metre gap in the bank marks where the original entrance once stood, with a causeway crossing the fosse to meet it. A modern field boundary cuts across the interior, dividing the rath into unequal sections, and in the smaller northern portion the fosse has been filled in over time, though its line can still be traced. Within the eastern interior, the footprint of a house survives, tentatively dated to the seventeenth century, a period when ruined or long-disused raths were sometimes reoccupied or built upon, their ready-made earthwork banks offering a degree of shelter and enclosure. Short linear field banks of unknown date are also visible inside, suggesting the space was reorganised at some point, perhaps more than once. Just outside the fosse to the south-east, a large pond, clearly constructed rather than natural, may belong to the same phase as the house, possibly serving as a water source or millpond for whoever occupied the site in that later period.