St John's Pro-Cathedral is located at 18 Victoria Avenue in Perth. It is the earliest Roman Catholic church building in Western Australia.
The Cathedral is constructed of brick which has been covered with lime render and painted ochre to resemble the colour of the original building. The gable roof is covered with shingles. The north and south facades are punctuated by arched windows. Buttresses have been placed at regular intervals down the length of these facades. The portico, which was removed in 1881, has been reconstructed at the western end of the building. The western gable end is punctuated by four arched windows, a pair above the portico and a single window either side of the portico. A lean-to extension is located at the eastern end of the southern facade. Entry to this section is through an arched door on the north facade. The church windows have clear glass set in wooden mullions. Those in the lean-to section are square, four paned windows.
The Pro-Cathedral of St John the Evangelist is an important building for the history of the Catholic Church in Western Australia. It was the first Catholic Church and would become the first Cathedral. It was the centre of Catholic life for the first twenty years of the Catholic Church in the Swan River Colony until the first St Mary’s Cathedral was completed in 1865.
In 1843 approval for the request was granted from Rome (Vatican) and Father John Brady, Father John Joostens (Belgian priest) and Patrick O'Reilly (a Catechist) were soon to arrive in Fremantle on the ship 'Water Witch'. Even though Father Brady was to stay in Perth for only a short time (two months) he was able to claim a land grant for the church, on Victoria Avenue. This was to be the site of the first Catholic Cathedral, the Church of St John the Apostle and Evangelist (St John's Pro-Cathedral). Construction commenced on 27 December 1843, with the foundation stone laid on 16 January 1844. In 1844 Brady left for Rome to ask for assistance and advocate the establishment of a new diocese for the Swan River Colony.