What makes it worth a second look is the way its defences are not uniform: the banks and fosse that define it are substantial on the upslope side, then quietly taper and disappear as the ground falls away to the north-east, where the inner bank reduces to a simple scarp and the outer ditch vanishes entirely.

This is a rath, the Irish term for a ringfort, the most common monument type surviving in the Irish countryside. Raths were typically the enclosed farmsteads of early medieval Ireland, roughly the fifth to the twelfth centuries, where a family and their livestock sheltered within a raised earthen bank. This example at Killavalla is slightly oval rather than circular, measuring 28.5 metres north to south and 35.2 metres east to west. Its bank is four metres wide, and where it survives best it rises over two metres above the outer ground level. Beyond the bank runs a wide, U-shaped fosse, a defensive ditch cut into the hillside to a depth of nearly two metres, with its own counterscarp bank on the far side rising to around two and a half metres. Together these earthworks would have presented a considerable obstacle on the uphill approach. The asymmetry of the defences almost certainly reflects the topography: the natural steepness of the slope on the north-eastern side offered its own protection, making elaborate earthworks there unnecessary. A stream runs roughly thirty metres to the north-west, close enough to have supplied the original occupants with fresh water. A later field bank running north-east to south-west has been joined to the outer bank in the north-western sector, a reminder that farmers in subsequent centuries continued to adapt and make use of structures that had long outlasted their original purpose.