Located in Athboy parish within the barony of Lune, this castle appears as a tower on the Down Survey maps from 1656 to 1658, those detailed cartographic records created in the aftermath of the Cromwellian conquest. By 1640, the castle and its surrounding 200 acres belonged to Lord Gormanstown, though even then the Civil Survey of 1654 to 1656 described it as ‘a ruinated castle and some cottages’, suggesting its defensive days were already long past.

The castle’s physical decline can be traced through historic Ordnance Survey maps like a slow motion demolition. The 1836 edition shows an oblong building measuring roughly 20 metres east to west and 13 metres north to south; a substantial footprint for what was likely a tower house typical of late medieval Ireland. By 1908, however, the structure had been reduced to a single wall running about 20 metres in length. Today, visitors searching for the castle will find only the barest traces: the foundations of the northeast corner, measuring about 3 metres by 2 metres, sit almost completely hidden beneath the sod about 6 metres north of a small stream.

These scant remains serve as a reminder of how quickly even stone fortifications can vanish from the landscape when abandoned. The castle at Castletown, once important enough to merit inclusion on early survey maps and to form part of a lord’s estate, has been reclaimed by the Irish countryside, leaving only archaeological hints of its former presence in this quiet corner of Meath.