It is an odd thing to find on a drystone cashel, that most landlocked of Early Medieval structures, and no one seems entirely sure what to make of it. The cashel itself is enormous, a circular enclosure roughly 128 metres in diameter, defined by a double-faced drystone wall that still stands most convincingly along its south-western and western arc. A gap of about three metres at the south-south-west may mark the original entrance, which would mean visitors have been passing through more or less the same point for well over a thousand years.

The place takes its name from the O'Drinans, a family whose recorded function was to distribute justice to the tribes of Hy Fiachra Aidne, the early Irish kingdom that once occupied this part of Connacht. That role, somewhere between judiciary and arbitrator, suggests the enclosure may have carried civic or ceremonial weight beyond mere agriculture or defence. A cashel, broadly speaking, is a stone-walled ringfort, a type common across Ireland but varying considerably in scale and purpose. This one has further complexity inside: a church and a cross-base, both now separate recorded monuments, sit within the interior, pointing to a religious dimension that overlapped with whatever judicial function the O'Drinans performed here. Later field walls subdivided the interior over the centuries, several of which were removed in 2002, restoring some sense of the original open space. Along the northern and eastern stretches, only the inner wall-facing survives, and from the east to south-east a curving field boundary traces what remains of the enclosing line.