TemplenagalliaghdooTemplenagalliaghdoo is a medieval church and National Monument in County Mayo, Ireland.LocationTemplenagalliaghdoo is located on a peninsula stretching into Lough Conn, immediately to the north of Errew Abbey.HistoryThe name means "Church of the Black Nun." This church was built on the site of a previous church founded in the 6th century; it may have been an oratory or nunnery.BuildingsTemplenagalliaghdoo is a small rectangular building with walls 50 cm thick and an entrance in the southwest, surrounded by a dry stone wall enclosure.