On a gentle east-facing slope at Knocktoby in County Galway, the pastureland gives nothing away at ground level, yet the site has been quietly puzzling over its own identity for the better part of a century. The 1921 edition of the Ordnance Survey six-inch map recorded what appeared to be an enclosure roughly 47 metres in diameter, its outline suggested by curving field boundaries. Whether that curve represented something deliberately built, a circular field arrangement of agricultural rather than ritual origin, or something older altogether, was never fully resolved.

When surveyors visited in May 1992, the question became harder rather than easier to answer. Land reclamation works had cleared the area, removing whatever surface traces might have lingered, and no physical evidence remained visible underfoot. The case did not close there, however. Aerial photography from the Ordnance Survey Ireland DigitalGlobe archive preserves a faint outline of the western half of the original curve, readable from above even where the ground itself has been smoothed over. It is this kind of spectral persistence, a shape legible only to a camera pointed downward from altitude, that keeps the site in the record at all. Archaeologists concluded that the evidence falls short of what would be needed to classify the feature as an archaeological monument, leaving it in an ambiguous category somewhere between a former field system and something that might once have been more.