About 300 metres west of Lough Gur in County Limerick, in a field of improved pasture that looks unremarkable from any angle, something lies buried that has never appeared on any Ordnance Survey map, leaves no shadow on aerial photography, and can only be detected by instruments sensitive to the faint magnetic signatures left by disturbed earth and stone. It is, in the most literal sense, a place that is invisible to the eye but legible to other means.

The site came to light in 2008, when a fluxgate gradiometer survey, a technique that measures variations in the earth's magnetic field to detect buried features such as ditches, walls, and pits, was carried out in the area around the famous Grange Stone Circle. Researcher Cleary, reporting that year, described what the instruments found as perhaps the most striking feature registered by the survey in that area. Two closely-set bands of negative magnetic gradient revealed a subcircular form, the inner band roughly 1 metre wide enclosing a space approximately 12.5 metres in diameter, and a broader outer band averaging 2 metres in width running concentrically around it to a diameter of over 20 metres. At the northeast, this outer band diverges slightly, extending northward for a short distance before fading out. The magnetic expression, Cleary noted, is suggestive of some form of enclosure, possibly defined by earthen or stone boundaries, though the survey could not resolve its full extent or date. The feature sits approximately 20 metres south of the Grange Stone Circle, one of the largest stone circles in Ireland, and within a short distance of two further stone circles and a possible anomalous stone grouping in adjoining fields, suggesting this corner of Limerick was intensively used in prehistory in ways still not fully understood.

For a visitor, there is nothing here to see in the conventional sense. The pasture shows no earthworks, no upstanding stones, no trace of what the survey detected below. The value of coming is contextual: standing in this ordinary-looking field beside Lough Gur, knowing that the ground beneath holds an unexcavated and as yet unexplained structure surrounded by one of the densest concentrations of prehistoric monuments in Ireland, gives the landscape a different quality. The Grange Stone Circle itself is accessible and well signposted; the field containing the buried enclosure lies immediately to its south, though it is private farmland and should be treated accordingly.