The Cathedral of Saints Peter and Paul was built between 1828 and 1861, designed by the architect Dominic Madden. Construction of the church was largely halted during the Great Famine. The church tower was completed in 1874. The parish church was elevated to pro-cathedral status in 1889, and to cathedral status in 1990.
The Cathedral of St Fachanan is an ancient cathedral that was originally an abbey church. St Fachanan founded a monastery on the site in the 6th century. The monastery went through a difficult period in the Middle Ages, being looted and burned. Rebuilt several times, the abbey church was repaired to its present form in the 1830s. The transept was fitted with a glass roof in 2005 to protect the remains of the three high crosses moved there.
Corcomroe Abbey is an old Cistercian abbey from the 13th century. The English Reformation led to the dissolution of Catholic monasteries in England and Ireland. In 1554, the abbey was given to the Earls of Thomond. The monks continued to cultivate the fields and maintain the abbey when circumstances permitted, but the political climate led to a steady decline. The last abbot, the Reverend John O'Dea, was appointed in 1628.