In a field in Toolestown, County Kildare, there is a monument that nobody can visit, touch, or even easily see from the ground. It exists, for now, primarily as a shadow in a photograph taken from space.

The site is a ring-ditch, a circular earthwork roughly nine metres in diameter whose outline emerges only as a cropmark, the differential growth of grass or grain over buried features revealing what the soil conceals. Where a buried ditch interrupts the subsoil, crops above it tend to grow taller and darker in dry conditions, drawing the hidden geometry of ancient construction up into the visible world for a few weeks each season. Ring-ditches of this kind are generally understood to be the eroded remnants of prehistoric funerary or ritual monuments, the outer ditches of round barrows whose central mounds have long since been ploughed flat. The Toolestown example came to notice through aerial imagery captured on 28 June 2018, when the conditions were apparently right to make the nine-metre circle legible from above. Its existence was subsequently recorded by Caimin O'Brien, working from details supplied by Jean-Charles Caillère, and uploaded in September 2019.