Most survive in Ireland only as faint cropmarks or degraded ridges, ploughed down over centuries of agricultural improvement. The example at Rathknock near Ballynacourty in County Galway is a different matter. Measuring 57.5 metres in diameter, it retains two concentric banks with an intervening fosse, that is, a ditch between them, making it a bivallate ringfort, a form generally associated with higher-status occupants than the more common single-banked variety.

The site sits on a gentle rise in rolling pastureland, and the earthworks are described as very well preserved, which places it among a more select group of ringforts that have escaped the levelling pressures of modern farming. A causewayed gap on the east-north-east side marks what would have been the original entrance, a common orientation for such sites, broadly aligned toward the rising sun. Antiquarians took note of the site across several decades: references appear in the work of Holt in 1912, Westropp in 1919, and McCaffrey in 1952, suggesting it was considered significant enough to be returned to repeatedly by those documenting Galway's archaeological landscape.