The structure is a rath, the Irish term for a roughly circular enclosure defined by a raised bank of earth, built during the early medieval period and used typically as a farmstead or high-status dwelling. What makes this one quietly interesting is not grandeur but erasure: a later field boundary, running from the south-east around through the south and west, has been laid directly over the ancient bank, compressing two entirely different phases of land use into a single confused feature on the ground.

The rath at Killeenavarra is subcircular in plan and measures approximately 24 metres in diameter, placing it at the smaller end of the scale for such enclosures, which in Ireland number in the tens of thousands. It was recorded by McCaffrey in 1952, who noted its poor state of preservation even then. The undulating pastureland surrounding the site is typical of this part of County Galway, and the southward orientation of the slope would have made the location a practical one for early farmers seeking shelter and light. By the time anyone thought to formally document it, the site had already been partially subsumed by the agricultural infrastructure of a much later era.