This one does neither. At Kilgask in County Tipperary, a circular enclosure exists almost entirely as an absence, visible only from the air and only then as the faintest of outlines pressed into the ground. At ground level, there is nothing to see.

What is known comes from a single aerial photograph taken in April 1973, which captured the ghostly trace of the enclosure on a low rise of ground, with bogland lying close to the south. Circular enclosures of this kind are common across Ireland and typically represent the remains of a ringfort, a type of enclosed farmstead used throughout the early medieval period, though without excavation it is impossible to say with certainty what this particular site was or when it was in use. The boggy ground nearby may help explain its survival as a cropmark, since subtle differences in soil moisture and vegetation growth are what make these features legible from altitude in the first place. On the surface, centuries of agriculture have smoothed away whatever once stood here.