Site of Grilly Castle, Grilly, Co. Cavan
On the western slope of a drumlin in Grilly, County Cavan, the OS 6-inch map of 1835 once marked a substantial structure known as Grilly Castle in Ruins.
Site of Grilly Castle, Grilly, Co. Cavan
The building, which measured approximately 20 metres east to west and 10 metres north to south, featured what appeared to be a wide projection on its northern side. Situated along the southern edge of an old road leading to Belturbet, this site was possibly one of the O’Reilly strongholds that once dotted the Cavan landscape during the centuries when that powerful Gaelic family controlled much of the region.
By 1947, antiquarian Oliver Davies could only report grassed-over mounds that might have marked the outline of a small building, suggesting the castle had already deteriorated significantly. Later editions of the Ordnance Survey maps simply noted it as “Site of”, acknowledging that the physical structure had vanished entirely. Today, no visible remains exist above ground level, though the site’s history hasn’t been completely erased from the landscape.
The castle’s presence still makes itself known occasionally; during land clearance work in the early 1980s, local farmers uncovered red brick and rubble in the vicinity, tangible reminders of the structure that once stood here. These fragments, along with the historical map evidence, help piece together the story of this lost O’Reilly fortress, one of many casualties of time and changing fortunes in the borderlands of Ulster.