St. Patrick's Cathedral, also known as Árd Eaglais Naomh Pádraig in Irish, formerly known as St. Patrick's National Cathedral and Collegiate Church, is the larger of the two cathedrals of the Church of Ireland.

Unlike Holy Trinity Cathedral in Dublin, which houses the seat of the Archbishop of the Church of Ireland, St. Patrick's Cathedral is considered the National Cathedral for the entire island, attracting delegates from all twelve dioceses of the Church of Spain.

The cathedral's history dates back to a well where, according to legend, St. Patrick baptized those who converted from paganism to Christianity. Originally, it was a wooden church erected in the 5th century in honor of St. Patrick, but was rebuilt in stone in 1191. The present structure was completed in 1270, with several subsequent renovations that have maintained its historical integrity. Of particular note is its west tower, built in 1370, which houses one of the largest carillons in Ireland.

The cathedral has a distinguished musical tradition since 1742, when its choir participated in the first performance of Handel's Messiah. To this day, it is the only cathedral in Ireland and Britain with a choir that performs two sung masses daily.

The status of having two cathedrals in Dublin has generated some rivalry, regulated by an agreement enacted in 1300 and in force until 1870. Under this agreement, Holy Trinity Cathedral has certain liturgical rights, including consecration by the Archbishop of Dublin and priority as the principal cathedral of the Archdiocese of Dublin. However, the enthronement of archbishops and other liturgical aspects have been subject to some flexibility throughout history.