No earthwork rises above the field, no stone marks the boundary, and there is nothing a walker would notice underfoot. The only evidence of what is there comes from aerial imagery, where a faint cropmark traces the outline of a roughly circular enclosure approximately 43 metres in diameter, defined by what appears to be a slight fosse, a shallow ditch, cut into the earth at some point in the past.

Cropmarks form when buried features affect how plants grow above them. A filled-in ditch, for instance, retains moisture differently from the surrounding soil, causing the vegetation overhead to grow or ripen at a slightly different rate, a difference that becomes legible from the air, particularly in dry summers when stress on crops makes the contrast more pronounced. The Mountpill enclosure was first reported by Jean Charles Caillére, and as of 2022 it remains visible only through enhanced aerial analysis. Circular enclosures of this kind are a familiar but not fully understood feature of the Irish landscape; depending on their date and context, they may represent the remains of a ringfort, a burial enclosure, or any number of other enclosed settlement or ceremonial forms spanning several thousand years. Without excavation, the Mountpill example cannot be assigned to any particular period or function.