Built in 1855 by the Irish Community of Bangor, this large brick church was designed by architect Patrick Charles Keely of New York. Designer of nearly 600 churches for the Roman Catholic Church in the eastern United States and Canada, Keely designed every 19th-century Catholic cathedral in New England built in the nineteenth century. Gothic in design, it was built to be a "symbol to the Irish community of Bangor of their identity within the community as a whole".
The church was constructed at a time when the Irish, in particular, were being persecuted for their lifestyle, the fact that they were immigrants and even for their religion by the
Know Nothing movement. It had not been long since the Know-Nothings had been associated with the tarring and feathering of a Catholic priest, Father John Bapst, in the coastal town of Ellsworth in 1851 and the burning of a Catholic church in Bath in 1854. Father John Bapst, it turns out, was the priest responsible for the construction of this church. The Irish needed a symbol of their identity and of their history and this church provided that symbol.
The church was built to seat 1,400, possibly the entire Irish population of Bangor at the time. Essentially unchanged since it was built, the major change that has taken place was the replacement of many of the original stained glass windows with tyrolean stained glass, though a few of the original glass remains. The church stands in the heart of what was once the Irish community in Maine.