What remains of this rath, roughly 36 metres in diameter, survives only in fragments: a portion of its outer bank and the fosse between the two original enclosing banks can still be traced from the south-south-east, around through south, and as far as west. Beyond that arc, the ground gives nothing away.

A rath, sometimes called a ringfort, is one of the most common archaeological monument types in Ireland, an enclosed farmstead of the early medieval period, typically defined by one or more earthen banks and ditches and used to protect a household, its livestock, and its stores. There are thousands of them across the country, yet many have been reduced by centuries of agriculture and land use to precisely this kind of ambiguous outline. At Castlebin, a trackway has cut directly through the monument, running from the north around through east to south-south-east, and the enclosing elements are broken by numerous gaps. The combination of the trackway and these breaches suggests sustained, pragmatic use of the landscape over many generations, the monument gradually subordinated to the needs of working farmland rather than deliberately cleared or demolished.