This one is remarkable for what does not. Near Brittas in County Tipperary, a circular earthwork once sat on a low natural ridge running east to west across gently undulating pastureland. By the time anyone thought to look for it carefully, it was already gone, erased by the construction of a railway line and, to its west, partially quarried away into a sand pit. Today there is nothing visible at ground level.

The site appears on the first edition Ordnance Survey six-inch map, published in 1843, where it is clearly marked as a circular enclosure. Such enclosures are among the most common archaeological monument types in Ireland, typically interpreted as the remains of ringforts, the farmsteads of early medieval Ireland, though some have earlier or later origins. By the time the revised edition of the same map was produced in 1952 to 1953, the enclosure was no longer indicated, suggesting it had been destroyed in the intervening period, most likely when the railway was laid through the area. A local landowner provided the detail about the sand pit to the west of the line, filling in the last piece of what happened to the remainder of the site.

What makes Brittas worth noting is less the absence of the monument itself than what that absence quietly illustrates. The 1843 OS mapping captured a landscape still carrying features that had persisted for perhaps a thousand years or more. Within little more than a century, the combination of industrial infrastructure and casual extraction had removed the site entirely. The ridge it stood on is still there, the pasture still rolls gently around it, but the circular form that once interrupted that landscape exists now only as a mark on a Victorian map and a landowner's memory of a sand pit.