The English architect of St. John's Cathedral, Philip Charles Hardwick was at work at Adare Manor when he was commissioned to design this Roman Catholic Cathedral. The main body of the church was constructed between 1856-61. The spire at 280 feet tall, is one of the three tallest in the country and was completed in 1883 to the designs of local architect M.A. Hennessy. St. Mary's Cathedral in Killarney and St. Macartan's in Monaghan are also the same height. Unlike other Roman Catholic Cathedrals of the period, the exterior of the church is quite severe, with very little external decoration except around the dooways. The windows are kept small and to a minimum, and there is only one external statue on the façade. This should be compared with the exteriors of Armagh and Monaghan where arcades of statues adorn the exterior. The upper levels of the soaring spire is more decorative than the mainbody of the cathedral, perhaps due to the different architect. The church has a fine interior which has been modernised in line with the Vatican II changes but without undue detrimental effect on the building.