St. Paul's Parish Church was re-structured from an existing building in 1838, when the old cathedral on the hill had fallen into disrepair. The policy of the 'Board of First Fruits' at this period was to provide new churches rather than repair ancient buildings. As a result, many fine churches fell into disrepair in the first half of the 19th century. Ardmore Cathedral, sadly, was one of those casualties.

The present church building was originally part of the cathedral complex at Ardmore (possibly a refrectory) and some architectural elements of the original ancient structure can still be seen within the church.

The font in the centre of St. Paul's Church, is thought to be a baptismal font of the early tudor period. It is octagonal in shape, the number eight representing re-generation. The decoration on the font is of late fifteenth century design. The font is thought to have been taken from the old cathedral and placed in St. Paul.

The ninety-eight foot round tower is one of the latest in Ireland dating from the twelfth century. The cathedral was build on the site of St. Declan's Monastery, but the present building was enlarged and many times throughout the ages. The oldest section of the cathedral extends from the chancel arch eastwards for about three quarters of the length of the chancel walls and has been dated to the ninth century.

The stone reliefs originally flanked the north doorway of the cathedral, but were moved to the west wall when the nave was extended at a later period.

A small oratory can be found in the graveyard that is locally known as the Beannachan. The building is of eighth century origin and the upper parts of the walls were restored by Bishop Mills (the Church of Ireland Bishop of Waterford) in the eighteenth century. It is thought to mark the site of St. Declan's grave.