There is a monastery on Mahee Island in Strangford Lough, Co Down which today presents itself as one of the best laid out monasteries known to us. It contains three concentric (reconstructed) cashel walls; the inner circle has the church, abbot’s house, graveyard and round tower; the second has workshops, a school and other burials; the third had trees, animals and gardens. The little museum has a reconstruction of the site and of the satchel in which thrhreat teachers carried their Gospel book
The foundation is attributed to St Machaoi in the fifth century; however there is, after several excavations no on site evidence earlier than the 7th. There is the oldest excavated tidal mill in the world giving a date of 619. There is also one of the earliest known but reconstructed sundials.
Its other name is Nendrum. The abbot of the monastery called Sedna was burnt in his own house by the Vikings in 974.