From the late 18th century onwards, many architects have put their mark on the Carmelite church on Clarendon Street. O’Neill & Byrne’s work between 1869 and 1877 was a new addition including a transept to the church, a library and other rooms. “With our present issue, we give and illustration of the front of a new addition to the above church, which is nearing completion, from the designs and under the superintendence of Messrs. O’Neill and Byrne, architects. The style is Romanesque. The plan comprises – transept, library, four sitting-rooms, hall and staircase. The transept is 53ft. in length by 30ft. in width, measured within the walls, and in height 37ft.6in. to apex of ceiling, which is groined in plaster to correspond with that of the old portion of the buildings. The library is 30ft. by 20ft. by 17ft.6in. in height, and is lighted from the roof. The front is composed of Dalkey granite in coursed ashlar; the dressings are of the same material and Portlamd. The arcades and windows are elaborately moulded, and enriched with columns of polished Dalkey granite. The wheel window is filled with stained glass, designed and executed by Messrs. Earley and Powells of Camden-street works. The figures in niches and on apex of gable have been execute by Messrs. Neill and Pearce, Great Brunswick-street. The carving on front by De Groot. The work was creditably carried out by Messrs. Meade and Son, Great Brunswick-street.” The Irish Builder, January 1 1877.