A shallow fosse, which is simply a ditch or trench cut into the earth, traces a rough circle across the ground. It measures roughly 22.7 metres in diameter. No wall survives, no upstanding stonework, no obvious structure. The enclosure that once occupied this space has been reduced to a faint depression, the kind of thing that registers as a slight wrongness underfoot before the eye quite catches it.

Circular enclosures of this type appear across Ireland in considerable numbers, and their purposes varied. Some were ringforts, the enclosed farmsteads of early medieval families. Others served ritual or funerary functions in prehistory. Without excavation, the Corbally example cannot be confidently assigned to either category, and the Ordnance Survey six-inch maps, which first recorded it formally, offer no interpretation beyond the bare outline. What the fosse preserves, then, is something genuinely unresolved: a boundary that once meant something specific to whoever dug it, now legible only as geometry in the grass.