Marked on both the 1837 and 1928 Ordnance Survey maps as “Ballylough or O’Flynn’s Castle” in distinctive gothic lettering, this site speaks to a once-powerful family whose influence has faded like the stones of their stronghold. Today, where the castle once stood, a modern house lawn conceals most traces of the medieval fortress, though a low boundary wall, roughly half a metre wide and 10 metres long, is believed to be the last visible fragment of the original structure.

The O’Flynns were chiefs of Síol Maolruain, a branch of the Uí Brionn sept, and whilst they weren’t native to Silmurry, their status was significant enough that they attended the inaugurations of the O’Conor kings. Their power began to wane after the fourteenth century, but they managed to hold onto lands around Lough O’Flynn, which still bears their name today. Beyond their role as local chieftains, the family served as erenaghs, hereditary stewards, of Assylin church near Boyle, maintaining both secular and ecclesiastical influence in medieval Roscommon.

Archaeological surveys from the 1970s recorded visible foundation remains, but these have since disappeared beneath suburban development. The castle’s near-complete erasure from the physical landscape makes it a poignant reminder of how Ireland’s medieval heritage can slip away, leaving only map references and fragmentary walls to hint at the power struggles and family dynasties that once shaped the region. The O’Flynn legacy endures primarily in place names and historical records rather than in stone and mortar.