The ringfort, known also as a rath, sits on a north-east-facing slope in poorly drained pasture, and the landscape around it has changed enough that you might walk past without quite registering what you are seeing. But read the contours carefully and a coherent enclosure emerges: a raised subcircular area roughly 28.6 metres across, ringed by a substantial earthen bank and a fosse, the fosse being the defensive ditch dug at the bank's outer foot and still visible as a shallow depression some four and a half to five metres wide.

Ringforts are among the most common archaeological monument types in Ireland, with estimates running into the tens of thousands nationally. They served primarily as enclosed farmsteads during the early medieval period, roughly the fifth to the twelfth century, and their earthen banks and surrounding ditches defined both a practical boundary and a social one. At Ballygilcash, the bank itself is between 4.6 and 6.7 metres wide, standing to an internal height of around 0.8 metres and an external height of between 1.55 and 2.3 metres on the outer face. The original entrance is still identifiable: a 4.4-metre break in the bank on the eastern side, with traces of a causeway that once carried it across the fosse. Inside, along the south-east to south-west arc of the bank's inner foot, there is a low terrace, and built up against the inner face of the bank at the south is a subrectangular raised platform measuring roughly 6.8 by 4.8 metres. This platform, standing 0.8 metres high, is thought to be the possible remains of a house, a structure that would have sat sheltered against the bank in the manner typical of early medieval domestic enclosures. A second possible rath has been identified approximately 95 metres to the east-south-east, suggesting this was not an isolated farmstead but part of a wider pattern of early settlement across this part of County Sligo.