Killaloe Cathedral dates from the transition between the Romanesque and Gothic periods. The font is decorated with arabesque ornaments. On the north side of the cathedral is a small oratory or chapel of a date far prior to the cathedral; and probably the original sanctuary of the holy man who founded the abbey. Its roof is very deep, and made entirely of stone; it has a belfry, and two doorways to the east and west.
A £200,000 restoration project involving the repair of a Romanesque doorway and the reconstruction of a 12th-century high cross, was completed in 2001. The Kilfenora Cross, embedded in the walls of the Gothic cathedral in the 1930s, is once again free-standing. The imposing 12-ft monument is now in the nave of the building.