The three-storey structure, built from roughly coursed limestone rubble, follows a distinctive Z-plan design with pear-shaped towers at the northeast and southwest corners. Its main entrance, a round-arched doorway on the western wall, leads through what may be either an original or later-added fore-building. The castle’s bawn wall extends from the northeast tower, curving back to meet the main building’s northwest corner, where nineteenth-century farmhouses have since been incorporated into the defensive perimeter.

The castle’s identity has shifted through the centuries, creating confusion even among mapmakers. The first edition Ordnance Survey six-inch map labelled it as ‘Derry Castle’, whilst the Civil Survey recorded the site as Derrymcegan castle. By 1840, maps showed Ireton’s Castle at an entirely different location near Belle Isle House, where a nineteenth-century windmill stands today. This windmill might have been constructed on the original castle site, though it’s equally possible that only one castle ever existed at the current location. The structure may have been refortified or rebuilt around 1650 by Henry Ireton, Cromwell’s son-in-law and Lord Deputy of Ireland, which would explain the name change from Derry Castle to its current designation.

The seventeenth-century fortified house remains remarkably intact, offering visitors a glimpse into Ireland’s turbulent past when such defensive residences were essential for survival. Its Z-plan layout, with diagonal towers providing flanking fire along all walls, represents a sophisticated defensive design that became popular during the plantation period. The ambiguity surrounding its various names and potential locations only adds to its mystique, embodying the complex layers of Irish history where Gaelic, Old English, and Cromwellian narratives intersect on the same patch of ground.