This one in Ballyandrew, in north County Cork, is visible only from the air, and only under the right conditions. A circular enclosure roughly thirty metres across betrays itself through cropmarks, the phenomenon whereby buried ditches and banks influence how vegetation grows above them, producing subtle colour and height differences in a field that, from ground level, looks entirely ordinary. A July 1969 aerial photograph taken as part of the Cambridge University Collection of Aerial Photography recorded the ghostly outline of a fosse, a defensive ditch, along with traces of an inner bank, and hints of a second concentric outer fosse running from north-north-west around to the south.

This is a rath, the Irish term for a ringfort, the most common monument type in the Irish countryside. These circular enclosures, defined by one or more earthen banks and ditches, were the farmsteads of early medieval Ireland, typically dating from roughly the sixth to the twelfth centuries. Most housed a single family and their livestock. The fact that this one survives only as a cropmark suggests the earthworks were levelled, whether by deliberate clearance or gradual agricultural erosion, at some point after the site went out of use. What makes the Ballyandrew example particularly interesting is its immediate neighbourhood. A second ringfort sits approximately fifty metres to the south-east, and a possible third lies around thirty metres to the south-west. Three such enclosures in close proximity points to a small but concentrated pocket of early medieval settlement, the kind of farming community that once gave this corner of Cork its shape and character.