Carved from reddish-brown sandstone, the doorway is ordered into four receding layers of ornament: scalloped capitals, spiral roll-mouldings, chevron fillets, and on one capital a pair of opposed ornithomorphs, possibly swans, facing each other on both faces of the stone. A hood-mould once terminated in carved anthropomorphic heads, though only the southern example survives in place. There is also the matter of the so-called Fiddle Stone, a rectangular block of the same reddish sandstone on which a figure playing a bowed stringed instrument is carved in relief; remnants of a moulded border suggest it may originally have formed part of a decorative frieze before being repositioned, at some point, onto the surviving jamb of the chancel arch.

The nave is thought to date from late in the twelfth century, its style consistent with the broader flowering of Romanesque building in Ireland during that period. The chancel and its arch were probably added shortly after 1200. Before the Office of Public Works conserved and partially rebuilt the structure during the 1880s, the church had been recorded and illustrated by the antiquarians Windele and Dunraven, which means there is a paper trail against which the subsequent conservation work can be measured. That comparison is not entirely flattering: some of the voussoirs, the wedge-shaped stones that make up an arch ring, were incorrectly repositioned during the works, and the hood-moulding over the doorway may in fact have been moved there from the chancel arch. An unusual pair of L-shaped stones projects from the external faces of the nave side-walls at a height of around 2.55 metres; their purpose is uncertain, though they may have helped stabilise the roof structure. Inside the chancel, a stone altar stands against the east gable beneath the window. Near its base is a small niche, possibly a relic cavity, which contains a number of human bones. A locally venerated object known as St Finan's altar stone was cemented onto the altar's surface until it disappeared at some point before the site's modern survey. An aumbry, a small wall cupboard used for storing liturgical vessels, is built into the chancel wall from slate flags and remains in place adjacent to the south window.