Ardfert Cathedral, Cathedral ruins in Ardfert, Ireland

Ardfert Cathedral is a ruined cathedral in Ardfert, County Kerry, dedicated to Saint Brendan. The site holds three medieval church ruins: the 12th-century main church, Temple Na Hoe from the 12th century, and Temple Na Griffin from the 15th century. The main church has a 15th-century transept and battlements, and its graveyard contains over 2,000 burials.

Ardfert was a Celtic monastery reputedly founded in the 6th century by Saint Brendan. The Synod of Ráth Breasail placed the cathedral for Ciarraige at Ratass in 1111, but it was moved to Ardfert by 1117, and the diocese ran from there until 1663. The roof was destroyed in the Irish Rebellion of 1641; the south transept was re-roofed later in the 17th century. After 1871 the disused site passed to the Board of Public Works.

The cathedral is dedicated to Saint Brendan, the 6th-century voyager monk said to have founded a monastery here. In the graveyard stand two further ruined churches, Temple Na Hoe and Temple Na Griffin, where local families buried their dead; over 2,000 burials were uncovered during excavation of the site.

The site is open to visitors for self-guided exploration at any time, allowing you to walk around the ruins without rush. Wear sturdy shoes because the ground is uneven in places and some walls show signs of age and weathering.

The main church holds an ogham stone among a group of early Christian and medieval grave slabs. Ogham is a script of notches cut along a stone edge, used for short inscriptions in early Irish, mostly names on memorial stones; it is not a language older than the cathedral. Excavation of the graveyard uncovered over 2,000 burials.