It is a rath, the most common type of early medieval settlement in Ireland, consisting of a raised circular bank with an external fosse, or ditch, enclosing a domestic space where a farming family would once have lived. This particular example measures roughly 23 metres across, which places it at the smaller end of the scale, and it has not worn its age especially well. The bank is overgrown, the fosse is difficult to make out, and a later field wall cuts clean across the monument at two points, running roughly north-north-west to south-south-east. That intrusion tells its own quiet story about how the landscape was redrawn in later centuries, with older structures simply absorbed into new field systems without much ceremony.

Raths were built in their thousands across Ireland during the early medieval period, roughly the fifth to twelfth centuries, and they survive in varying states across almost every county. They were not primarily defensive structures, despite the impression the earthworks might give; they functioned more as enclosed farmsteads, marking status and providing a degree of security for livestock. The Fiddaun example was recorded by McCaffrey in 1952, catalogued as entry number 144 in what was then a growing body of field survey work attempting to account for these monuments before agricultural change erased them entirely. Many did not survive that period. This one persists, though barely.