St. Patrick's Cathedral, Armagh

By 1854 there had been a revolution in ecclesiastical architectural taste in Ireland. The Perpendicular Gothic style of the sixteenth century had fallen from favor and earlier Medieval Gothic had become more popular.

The new architect,  McCarthy, did not wish to continue to build in the now unfashionable Perpendicular Gothic used by his predecessor. His solution was to start building a Decorated Gothic Cathedral of the fourteenth century on top of the purportedly sixteenth century foundations and walls.

St. Patrick's Cathedral is in Armagh, Northern Ireland. It serves as the Roman Catholic cathedral of the Archdiocese of Armagh, the original medieval Cathedral of St. Patrick having been retained by the state church, the Church of Ireland, at the time of the split of the Irish Church during the Reformation. 

Since the Irish Reformation under Henry VIII, no Catholic Archbishop had resided in Armagh. Since the seventeenth century, the majority Catholic population of Ireland had lived under the rigours of the Penal Laws, and the public public practice of Catholicism was almost completely extinguished and all Churches existent at the time of the enactment of the laws were ceded to the Established Church. By the end of the eighteenth century, there were few Catholic churches and no cathedrals in existence in Ireland. Following Catholic emancipation in 1829, the need to construct churches and cathedrals to serve this population became apparent. Construction was delayed by lack of available land for purchase, the Irish Potato Famine, a cholera epidemic and the death of the original architect and the deaths of five Archbishops.