St. Mary's Pro-Cathedral
One of the few Roman Catholic churches in Ontario retaining its pre-Confederation character, St. Mary's was erected in 1859-60 during the episcopate of Bishop John Farrell to replace a building destroyed by fire. It was designed by Frederick Kortum, a German-born architect who died before the church was completed, and was built with volunteer labour provided by parishioners. Gothic Revival in style, the imposing structure is distinguished by its massive bell tower and stone trim. The church's most impressive feature, however, is its magnificent interior with elaborately-carved high altar fashioned by Montreal architect Zépherin Perrault and fine stained-glass windows made in Bavaria. The seat of the Bishop of Hamilton until 1927, St. Mary's now serves as a substitute cathedral for the diocese.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.