Nearly 3.5 metres tall and carved from granite, it is largely plain, which is itself unusual for an Irish high cross, a form that typically carries elaborate scriptural carvings across every surface. Here there is almost nothing: a few sunken recessed panels on the sides of the shaft and on the underside of the ringed wheel, and blank faces on both sides of the head. Some scholars have suggested this plainness is not a stylistic choice but an accident of history, that the cross was simply never finished. To complicate matters further, the cross you see today is not quite the cross that was originally raised. When John O'Donovan visited in 1838, he found the upper portion lying on the ground to the west of the shaft, apparently blown off by a storm. When the cross was eventually re-erected, a portion of the shaft had to be shortened and shaped into a dowel to fix the two sections back together. A tenon cut into the very top of the head indicates there was once a capstone as well; no trace of it has ever been found.

The site has roots that stretch back to the sixth century. The monastery here was founded by St Finnian of Clonard, one of the most influential figures in early Irish Christianity, credited with teaching many of the saints who went on to found monasteries of their own across Ireland and beyond. The Romanesque church whose ruined walls still stand some 12 metres to the south-east of the cross was built on the footprint of that earlier monastic settlement. Romanesque in the Irish context refers to the rounded-arch architectural style that arrived in Ireland during the twelfth century, giving a rough sense of when the standing church was constructed over what would have been a much older foundation. The cross itself, resting on a stepped pyramidal base roughly half a metre high, belongs to that earlier, pre-Romanesque tradition of carved stone monuments associated with the earliest centuries of Irish monasticism.

Just east of the cross, and easy to overlook, is a large earthfast block of granite that has sunk considerably over the centuries, now standing only around 43 centimetres above the ground. Cut into it is a deep, V-profiled basin, roughly 84 centimetres long and 55 centimetres deep, with no drain hole. It is almost always full of water. O'Donovan recorded in 1838 that local belief held the water to be blessed, carrying the virtue of St Finnian himself, and capable of curing headaches. The logic, as he noted it, was straightforward enough: the stone retains the saint's blessing, and imparts it to every drop of rain that falls in.