In a field at Garrisker in County Kildare, something circular lies just below the surface, invisible to anyone walking past but readable from the sky. A cropmark, roughly fifty metres in diameter, betrays the outline of an ancient enclosure, the kind of feature that only reveals itself under the right conditions: dry summers, when buried ditches or disturbed soil cause crops above them to grow at a slightly different rate, creating faint rings or lines legible in aerial photographs but otherwise undetectable at ground level.

The enclosure at Garrisker came to light through a Google Earth photograph taken on 28 June 2018, with the detail first noticed and passed on by Anthony Murphy, a researcher with a long record of identifying such features across the Irish midlands and east. Circular enclosures of this scale are a common but still poorly understood feature of the Irish landscape. They may represent the remains of a rath or ringfort, a type of enclosed farmstead typically built between the early medieval period and the Norman arrival in the twelfth century, though some enclosures of similar form are considerably older. Without excavation or further survey, the Garrisker example cannot be dated with any confidence, and its function remains an open question.