The enclosing bank rises to over two metres, and the roughly circular interior spans around 37 metres across, a scale that suggests this was once a place of real consequence rather than a modest farmstead boundary.

This is a rath, the Irish term for a ringfort enclosed by earthen rather than stone banks. Ringforts were the most common settlement type in early medieval Ireland, built and occupied roughly between the fifth and twelfth centuries, and thousands survive across the country in varying states of preservation. They typically enclosed a farmstead and its associated structures, with the bank and its accompanying fosse, an external ditch dug to provide the material for the bank itself, serving both as a practical boundary and a marker of status. At Rossnacaheragh, the fosse survives to a depth of 1.3 metres and runs along the south-south-east to south-east arc of the monument, suggesting either selective erosion elsewhere or deliberate construction priorities on the more exposed approaches to the slope.