Teampall Feichin is the main visible ruin on Omey, a small stone church associated with St Feichin and the island's early Christian past. Its power is mostly in the setting: low walls, open grass, and the Atlantic air around a place that was once important enough to draw worshippers across the sand.
The site is exposed and modest, so come for atmosphere rather than grand architecture. It makes the best historical focus for a walk around the island.