Today, only the mortared stone foundations of three walls remain visible; a rectangular structure with walls measuring 5.6 metres in length and 0.6 metres thick. The relatively thin walls suggest this particular structure dates from after 1700, rather than being part of the original medieval castle. Historical maps tell the story of the castle’s decline: the 1837 Ordnance Survey 6-inch map shows it as an upstanding building marked ‘Castle (in ruins)’, whilst by the 1911 revision it appears merely as ‘Castle (Site of)’, indicating the structure was levelled sometime during those intervening decades.

The castle’s earlier history proves more intriguing. The Down Survey map of Leny parish, drawn between 1654 and 1659, depicts Farrow Castle as a tower house standing on lands owned by Sir Thomas Nugent, described as an ‘Irish Papist’ who held 200 acres of arable land in the townland. The survey’s terrier notes that Leny parish contained six castles in total, with single castles at Rathbennett, Farrow, Cullanhue, and Ballinafid, and two at Ballinilack, suggesting this area was once densely fortified.

Just north of the castle site marked on the old maps stand the remains of a strongly built stone house, complete with a fireplace at one end and a substantial buttress supporting its northern wall. Within this house, a fragment of dressed limestone now serves as a fireplace lintel, but closer inspection reveals it to be a medieval jambstone, likely salvaged from a door or window of the original castle; a tangible link to the medieval structure that once dominated this corner of County Westmeath.