The one at Drumavaddy in County Cavan breaks that pattern quietly but clearly. Its internal diameter of just 18.4 metres, measured on a north-north-west to south-south-east axis, places it well below the typical range, making it an oddity even within a monument type that numbers in the tens of thousands across the island.

A rath, to use the Irish term, is generally understood as a roughly circular enclosure defined by one or more earthen banks and ditches, used as a farmstead and place of security from roughly the sixth to the twelfth centuries. At Drumavaddy, that enclosure takes the form of a raised circular platform surrounded by a low earthen bank and a narrow fosse, the ditch that typically runs just outside the bank, which here is partly waterlogged. Both features appear to have been altered at some point in the more recent past, which complicates any reading of the original layout. No trace of the entrance survives in a recognisable form, so how people moved in and out of this small enclosure remains unclear. Locally, it has simply always been called a fort, that word carrying the weight of long memory even when the specific history has faded.

What exactly the site was used for is an open question. Its modest size might suggest a function other than a family farmstead, perhaps an enclosure for animals, a boundary marker, or something more specialised. The later modifications to the bank and fosse mean the ground itself offers few straightforward answers.