The Down Survey barony map, created between 1656 and 1658, shows a roofless gabled structure at what was then called Irishtowne in Mapperstowne parish. This detailed cartographic record, one of the first comprehensive surveys of Irish land ownership, captured the building when it was already in ruins, suggesting it had been abandoned or destroyed during the tumultuous period of the Cromwellian conquest.

The Ordnance Survey Letters, those invaluable 19th-century documents that recorded local history and folklore, also mention a castle in Irishtown. Today, locals still refer to one particular field as ‘the Castle Field’, keeping alive the memory of a structure that has left no visible traces above ground. This oral tradition, passed down through generations, serves as the only tangible link to what was once likely an important defensive structure in medieval Louth.

Archaeological surveys conducted in 1986 and 1991 confirmed the historical references but found no surface evidence of the castle’s remains. The precise location remains uncertain; whether the stones were robbed for building materials over the centuries, or whether foundations still lie buried beneath the soil, waiting to be discovered. What we do know is that this phantom castle joins the ranks of Ireland’s lost heritage sites, structures that exist now only in old maps, field names, and the collective memory of local communities.