The ringfort at Fortgrady sits on the south-eastern end of a gravel knoll, hemmed in by trees, briars, and bracken, its double earthen banks and intervening fosse, the ditch cut between defensive banks, still readable in the landscape if you know what to look for. The fosse is cut deep into the gravel ridge, reaching around seven metres in depth on the northern, eastern, and western sides, while the outer bank still rises to about one and a half metres. A causeway crosses the fosse on the south-eastern side, where the banks are less sharply defined and the interior ground rises noticeably above the level of the surrounding field.

The site's possible connection to the Synod of Ráith Bressail, held in 1111, is what lifts it out of the ordinary run of Cork ringforts. That synod was an extraordinary moment in the reorganisation of the Irish Church, establishing a formal diocesan structure across the island for the first time, dividing Ireland into two provinces, Armagh and Cashel, each with its own set of suffragans. It was convened under the reforming archbishop Cellach of Armagh and the papal legate Gille of Limerick, and the decisions taken there reshaped Irish religious life for centuries. The identification of this particular rath as the likely location of the synod rests on scholarship published by Candon in 1984, and the place-name Ráith Bressail, meaning the rath of Bressail, clearly points to a ringfort setting. That a now-overgrown earthwork in north Cork, eighty metres from the Blackwater, should be the candidate is not implausible; the river corridor was a significant axis of movement and power in early medieval Munster.