A cashel is a type of ringfort enclosed by a drystone wall rather than an earthen bank, and the one at Seefin once measured roughly 44 metres across. Today, almost nothing of that wall remains standing; a few external facing-stones are the only clear evidence of what was once a substantial enclosure. The material did not simply disappear. It was almost certainly recycled into the Daly monument, a commemorative structure that now occupies a large section of the north-east quadrant of the interior, effectively cannibalising the prehistoric for the purposes of the recent dead.

The Daly monument marks the hanging of a man in 1820, the circumstances of which are not recorded in surviving accounts attached to the site. What is clear is that someone considered the event significant enough to raise a substantial memorial, and that the ruined cashel wall provided a convenient quarry of already-dressed stone. This kind of reuse was common across rural Ireland, where ancient drystone structures were routinely dismantled to build field walls, farmhouses, or, in this case, something more deliberately commemorative. Elsewhere within the old cashel enclosure, traces of a possible house site survive to the east of the monument, and the access point to a souterrain, an underground stone-lined passage typically associated with ringforts and used for storage or refuge, is also visible nearby.