The one at Coolagh, in County Galway, is more of a puzzle. Sitting on a low hummock in open grassland, its circular form survives only in fragments, and reading it requires some patience. The site is roughly 35 metres in diameter and was originally defined by two earthen banks with a fosse, a defensive ditch, running between them. What remains is an uneven record of survival and loss: the inner bank is legible along the north-western and south-western arcs, but elsewhere it has collapsed to little more than a degraded scarp, a gentle slope in the ground where a more substantial earthwork once stood.

A rath, the Irish term for this type of enclosed farmstead, would typically have housed a single family and their livestock during the early medieval period, roughly the fifth to twelfth centuries. They are among the most common archaeological monuments in Ireland, numbering in the tens of thousands, yet each one is shaped differently by the centuries that followed its use. At Coolagh, the south-western portion of the outer bank has vanished entirely, overlain by a later field boundary whose builders apparently found the old earthwork a convenient source of material or simply an obstacle in the way. The fosse fares slightly better, surviving along the north-western and south-eastern stretches, though overgrowth obscures it through much of the southern arc. Only the north-western segment of the outer bank remains at all visible.