On the 1837 Ordnance Survey Fair Plan of Mullingar town, a D-shaped earthwork appears just over half a kilometre to the north-east of the town, labelled simply as 'Fort', its outline traced in dotted lines with some stippling and a straight edge running along its southern side. By the revised 25-inch Ordnance Survey edition of 1910, that same spot is occupied by a gravel pit, shown as a circular depression. Today, neither feature is visible on the ground.

The earthwork occupied gently sloping pasture with the River Brosna lying to the south-east, a setting entirely consistent with a ringfort. Ringforts, the most common monument type in the Irish countryside, were typically circular or oval enclosures defined by one or more earthen banks and ditches, used as farmsteads during the early medieval period. Their positioning on well-drained slopes near water sources was deliberate, practical, and repeated across the country in the thousands. This particular example sat within a landscape already marked by earlier and later activity: a Franciscan friary and a corn mill stood roughly 280 metres to the south. The friary's proximity hints at a medieval and post-medieval neighbourhood of some density just outside the town.

Sometime between those two map surveys, the earthwork was quarried away, its material presumably extracted for road-making or construction fill, a fate that overtook a great many ringforts during the nineteenth and early twentieth centuries as demand for gravel grew alongside expanding towns and infrastructure. Even the gravel pit that replaced it has since been filled or graded over, leaving a stretch of pasture that gives no indication of what once stood, or what was removed.