This one in Knightswood, County Westmeath, does almost the opposite: it is a circle that has nearly stopped being a circle, a ringfort so levelled or degraded that its outline survives mainly as a ghost visible in aerial imagery rather than anything you could easily walk around and recognise on the ground.

A rath, to use the Irish term, is a type of ringfort typical of early medieval Ireland, usually consisting of a roughly circular area enclosed by an earthen bank and ditch, within which a farming family would have lived. This particular example, roughly 35 metres in diameter according to its depiction on the first edition Ordnance Survey six-inch map, once held that familiar enclosed form. That nineteenth-century map shows a circular bank still coherent enough to record. By the time satellite imagery was captured between 2011 and 2013, only a faint outline remained, the bank long since slumped or ploughed into the surrounding poorly drained grassland. It sits approximately 170 metres east of another ringfort, suggesting this was once a landscape with a meaningful concentration of early settlement, two enclosures in relatively close proximity in what is now unremarkable Westmeath farmland.

What makes the site quietly interesting is precisely its near-invisibility. The first edition Ordnance Survey maps, produced in Ireland during the 1830s, captured many earthworks that have since diminished or vanished entirely, making them an inadvertent record of loss. This monument in Knightswood belongs to that category: better understood through a nineteenth-century cartographer's pen and a digital satellite pass than through anything currently standing above the waterlogged grass.