Just west of Rosslare Harbour, on flat ground roughly 420 metres from the shoreline, a patch of overgrown land behind farm buildings preserves a few low wall footings. The name has stuck, the designation has persisted across successive Ordnance Survey editions, and yet the structure it commemorates was in all likelihood a substantial house belonging to a prosperous landholding family.

That family was the Synnotts, and their presence at Ballygerry can be traced across a turbulent century and a half of Irish history. A memorial stone at Ballyconor Big, dated 1570, records Katherine Synnott as a daughter of Simon Synnott of Ballygerry. Phillip Synnott held the property from the Crown at his death in 1590, and Simon Synnott is recorded as holding 185 acres here in 1640 in the Book of Survey and Distribution, a mid-seventeenth-century document compiled to register land ownership following the Cromwellian settlement. That settlement bore directly on the family: a John Synnott of Ballygerry was listed for transportation in 1653, along with four dependents, one of the thousands of Catholic landowners displaced in that period. The Down Survey of 1656 to 1658, a remarkable cartographic project that mapped confiscated Irish lands in extraordinary detail, depicts both a substantial house and a windmill at Ballygerry. By around 1840, the scholar John O'Donovan noted that no part of the structure remained visible above ground, though local knowledge still kept the site alive. Archaeological monitoring carried out around 80 metres to the west in 2008 found nothing, leaving the wall footings as the only physical trace of what the Synnotts built and lost.