St Senan founded a monastery here in the 6C.
There is an oratory (St Senan’s) reputed to be where, in an adjacent small building, the saint lies buried. Just outside the oratory is a 10C Cross Slab.
The brow of the island is called the ‘Hill of the Angels’, so-called after the assistance given to St Senan by St Michael to get rid of a monster. On it are the remains of another church.
The large Cathedral of St Mary has undergone much rebuilding but parts of it go back to early times. Next to it is a 12C Romanesque church.
The Church of the Dead, near the sea, dates from 14/15C.
The Round Tower is the tallest in Ireland measuring 120 feet and is the only tower to have its entrance at ground level. Nearby is a Holy Well.
St Connera’s grave is said to lie on the SW shore.
There are some outdoor altars on the island.