One of the last almost complete buildings within the site at St. Mullins is marked as The Oratory. It’s a simple rectangular structure of 7.3 m x 4.9m, made from uncoursed granite rubble. The side walls are about 2 meters in height with the gable ends approx 5 meters. In the west gable there is an impressive lintelled doorway locked steel gate to prevent access for some strange reason. There are two lintelled opes in both the north and south walls and a rectangular ope in the east gable which is now blocked from view by a number of medieval memorial stones which rest inside the structure.
The building is now used as a mausoleum for Kavanagh family (descendants of the Mac Murchada kings of Leinster). To the east of the oratory is an adjoining structure which can be entered. To my surprise it was here that I found a memorial stone for Art Mór Mac Murchadha Caomhánach or Art MacMurrough Kavanagh. He was one of the last effective kings of Leinster and from what I have read about him to date showed some redeeming qualities by constantly kicking Anglo Norman butt in the region.
I guess this was the least that he could do considering it was one of his ancestors whom brought about the Norman invasion of Ireland in the first place.Art is said to have died in New Ross, Co. Wexford in 1417 after being allegedly poisoned. It was said that he was so popular that by the time his body arrived at St. Mullins for burial, the funeral procession was still leaving New Ross which is about 15km away.