On Tallaght Hill in south County Dublin, in a stretch of rough upland pasture, there are traces of what may be prehistoric ring-ditches that cannot be seen at ground level at all. They exist, as far as direct observation goes, only as a faint discolouration in the grass, readable from the air but otherwise indistinguishable from the surrounding hillside.

A ring-ditch is the circular trench that once surrounded a burial mound or other funerary monument; over centuries the raised earthwork erodes away entirely, but the ditch, having been cut deeper into the subsoil, retains enough moisture to produce slightly different vegetation above it, which is what makes it legible from altitude. The Lugmore features came to attention through oblique aerial photography carried out by Leo Swan in the 1980s, when crop and vegetation marks showed the possible outlines of ring-ditches in the pasture. They lie to the south of a cluster of already-recorded prehistoric monuments, including a cist burial and a ring-barrow, both listed under SMR 21:52/53. A cist is a small stone-lined grave, usually covered by a capstone, while a ring-barrow is a low burial mound enclosed within a circular ditch or bank. The proximity of these confirmed monuments makes the aerial traces all the more plausible as the remnants of a once-larger funerary landscape on the hill.

Tallaght Hill sits within what is now a suburban and semi-rural fringe to the south of Dublin city, and the rough pasture in question is not a managed heritage site with signage or public access infrastructure. Visitors who do make it to the area should be aware that there is simply nothing to see at ground level; the significance of the place is entirely in what lies beneath the turf. The value in coming here is more contemplative than visual, standing within a landscape that aerial photography has revealed to be considerably older and more layered than it appears on foot.