The only evidence of its existence comes from the air, where, under the right conditions, the buried feature betrays itself as a cropmark, a phenomenon that occurs when buried ditches or walls affect the growth rate of overlying vegetation just enough to leave a faint but legible shadow in aerial photographs.

Cropmarks of this kind have been central to Irish archaeological discovery since systematic aerial photography began to be used as a survey tool. The enclosure at Killegar was recorded through this method and appears on aerial photographs held in the Geological Survey of Ireland Air Photography collection. Oval or circular enclosures of broadly similar proportions are found widely across Ireland and can date from the prehistoric period through to the early medieval, sometimes representing the remains of a ringfort, a farmstead enclosed by an earthen bank and ditch, or an even earlier ceremonial or funerary boundary. Without excavation, it is not possible to say which period this particular example belongs to, and the notes offer no additional dating evidence.

Because the feature is not visible at ground level, there is nothing for a visitor to see in the conventional sense. The interest here is almost entirely in the idea of the place, that an entire enclosed space, lived in or ritually used by people who have left no other trace, persists only as a faint pattern readable from several hundred feet up in the sky on a dry summer's day when the crops are growing unevenly over something they cannot quite forget.