In a grass field near Kilbreedy in County Tipperary, an earthwork exists that reveals itself only from the air, and even then only under particular conditions. It was first identified as a cropmark on an aerial photograph taken in April 1974, when the differential growth of crops or grass overhead betrayed the buried outlines of something below. At ground level, nothing is visible at all.

Cropmarks form when buried features, such as filled-in ditches, walls, or pits, cause the soil above them to retain moisture or nutrients differently from the surrounding ground. In dry conditions, the vegetation directly above a buried ditch often grows taller or greener, while soil compacted by an ancient wall produces the opposite effect. The photograph from 1974 caught exactly this kind of faint signal, placing the earthwork immediately to the north-east of a ringfort, the circular enclosed farmstead that was the standard unit of rural settlement in early medieval Ireland. That ringfort itself sits roughly forty metres to the north of the earthwork, and there is a possible further enclosure about forty metres to the south. Two more enclosures lie within a kilometre to the south-west, suggesting that this part of Tipperary was once considerably busier than the quiet grassland now implies.

There is little point in visiting with any expectation of seeing the earthwork itself. What a visitor would find is open farmland, a nearby ringfort, and the kind of unremarkable field that conceals more than it shows. The interest here is almost entirely in what the aerial record preserves: a snapshot of a landscape that has otherwise been completely smoothed over.