These evocative ruins look more like a crumbling parish church than a cathedral, but that’s exactly what stood here until the hamlet of Aghadoe was sacked by the forces of Oliver Cromwell in 1652. Ivy grows along a roofless nave, and decaying stone walls give way to a hillside graveyard. The tiny round tower, a few yards away, is the sole remnant of a monastery dating from 1027. Adjacent to the ruins is a breathtaking viewpoint overlooking the Lower Lake, 1.6km (1 mile) away. Squint and you can also see Ross Castle on the far shore. There’s a small (free) parking lot next to Aghadoe Heights Hotel just across the street.