Ardfert Cathedral sits on the site of a monastery founded by locally-born St. Brendan the Navigator in the 6th century. It features three medieval churches, the largest of which was begun in the 12th century, although much of what remains primarily dates from the mid-13th century.

It has a Romanesque west doorway, a magnificent east window next to a row of nine lancet windows, an impressive feature that it shares with the nearby contemporary friary. A small transept and battlements were added in the 15th century.