This is a rath, the Irish term for a ringfort, the most common type of early medieval settlement monument in Ireland. Thousands were built across the country between roughly the fifth and twelfth centuries, serving as enclosed farmsteads for single families or small communities. Most people drive past them without a second glance, reading them as nothing more than a slightly odd bump in a field.

The Shanavoher example is modest in scale but well-defined. The circular enclosure measures approximately 26.6 metres in diameter, its boundary formed by a partially stone-faced earthen bank. Where an earthen bank is reinforced on its inner or outer face with stones rather than built entirely from drystone masonry, it suggests a degree of deliberate construction that goes beyond simply heaping up excavated soil. The bank here stands around one metre high on the interior and rises to about one and a half metres on the exterior along its south-west to north-east arc, with a lower, less pronounced rise continuing around to the east. A laneway runs along the western side, skirting the bank closely enough to suggest the two features have coexisted for some time, the modern agricultural landscape quietly accommodating the ancient one rather than erasing it.