It is not a ruin in the conventional sense; there are no collapsed walls or fallen stones. What remains is the earthwork itself, and that is the point.

This is a rath, the most common type of ringfort found across Ireland, built during the early medieval period, roughly between the fifth and twelfth centuries. A rath consists of one or more earthen banks enclosing a roughly circular space, typically used as a farmstead or the defended residence of a local farming family. The Ballycardeen example measures approximately 51.6 metres north to south and 50.8 metres east to west, making it a respectably sized enclosure. Its bank still stands around 2.1 metres high, which gives a fair sense of how imposing these structures would have felt at ground level to anyone approaching without an invitation. Around the outside runs a fosse, the shallow ditch from which the material for the bank was originally dug, though this ditch is absent along the south-east and north-west stretches of the circuit. A pathway cuts east to west across the northern half of the interior, evidence that the land has been in continuous agricultural use long after the ringfort's original purpose was forgotten. The enclosure sits in open pasture on the hill, which means the earthwork has been spared the kind of disturbance that comes with ploughing, and the form of the bank has survived in reasonably clear condition.