St Canice's Cathedral, also known as Kilkenny Cathedral, is a cathedral of the Church of Ireland in Kilkenny city, Ireland. It is in the ecclesiastical province of Dublin.Previously the cathedral of the Diocese of Ossory, it is now one of six cathedrals in the United Dioceses of Cashel and Ossory.HistoryThe present building dates from the 13th century and is the second longest cathedral in Ireland, after St. Patrick's Cathedral, Dublin. Beside the cathedral stands a 100 ft 9th-century round tower. St Canice's tower is an example of a well-preserved 9th-century "Celtic Christian" round tower. It is dedicated to St Canice. It is one of only two such medieval round towers in Ireland that can be climbed to the top.The cathedral stands on an ancient site which has been used for Christian worship since the 6th century. In the 1120s the see of Ossory was moved from Aghaboe to Kilkenny.Following the English Reformation, the reformed church in Ireland was established by decree of the Irish Parliament to become the state church in the Kingdom of Ireland as the Church of Ireland, taking possession of most church property (and so retaining a great repository of religious architecture and other items, though some were later destroyed). The substantial majority of the population, however, remained faithful to Roman Catholicism, despite the political and economic advantages of membership in the state church. Since St Canice's Cathedral was taken over in this way, Roman Catholic adherents were consequently obliged to worship elsewhere. St Mary's Cathedral in Kilkenny was later built for the Roman Catholic diocese.