The ruined medieval church at Killadoughran, also recorded under the older place-name forms 'Culhotocran' and 'Colloghdoghran', sits within a polygonal graveyard, an unusual shape for an Irish ecclesiastical enclosure, and is surrounded by a cluster of related sites: a lough, a castle, and a ringfort all within a few hundred metres. What makes the place quietly strange is not its scale but its ambiguity. The building has been misread for generations. It looks, at a glance, like a nave-and-chancel church, the standard two-part arrangement common in medieval Irish ecclesiastical architecture, with a longer nave for the congregation and a narrower chancel at the east end for the clergy. But the narrower eastern section sits at a lower level than the main body of the church, and its walls are significantly thinner, both details pointing to a later, post-medieval chapel added against the outside of the original east wall rather than a true chancel built as part of a single design.

A nineteenth-century account by Cogan, writing between 1862 and 1870, recorded the old sanctuary as measuring fifty-seven feet by nineteen, and noted a headstone inside the nave commemorating a Capuchin friar, a detail that hints at continued Catholic use of the site through the post-Reformation period. The church itself appears to have begun as a simple single-cell structure, its walls built from rough, undressed stone laid in irregular courses. Today the tallest surviving masonry reaches about two metres at the northwest corner, with the north wall of the nave also partially standing; elsewhere, grassed-over footings are all that remain. Scattered through the surrounding graveyard are fragments that speak to what has been lost: a possible window sill with moulded edges, a stone with an oval cross-section and raised ribs that may have been a window mullion, and a carved stone likely serving as a font base, decorated with a raised quatrefoil and circular mouldings with pointed projections. A medieval font was removed from the site some years ago. Local knowledge adds that a carved stone head, once associated with a feature called 'the Court' on a nearby hillock, is also gone, along with at least one other decorated stone.