When Father Mollinger prepared to build his chapel, he chose a design appropriate to the sacredness of the collection of relics to be preserved there, a space of great beauty to inspire devotion and prayer. A collection of relics as vast as this would be honored in a structure the size and scale of a basilica. As this was not possible, Mollinger chose a building on a smaller scale, along the lines of a chapel royal. Such chapels exhibited the highest quality in materials, design and color.
The original chapel was roughly thirty by thirty feet, laid out in a cruciform plan. Set on a sandstone foundation, it was constructed of thick brick load-bearing walls laid in an English bond pattern and topped with a handsome corbeled cornice. The roof is a hipped design covered with slate and was originally crowned by a cupola glazed with stained glass. This decorative dome was removed at some point in the chapel’s history and replaced by the present skylight. The main entry to this smaller chapel of 1883 stood in the area of the present-day central arch; a smaller entrance was located on the side facing the rectory and can still be seen in the covered passageway.
The later nave addition completed in 1892 defines the architectural style of Saint Anthony Chapel today. Erected to house the large Stations of the Cross, the extended nave with its bell towers is almost one and a half times longer than the original chapel. The style of the addition is Romanesque, based on Roman design and characterized by rounded arches, vaults, and towers, along with thick massive walls of rough-cut stone. This architecture communicates the qualities of strength and stability, solemnity, and mystery. The Romanesque style was popular in Europe and America from 1880s until the turn of the century; a fine example of this revived style in our city is the Allegheny County Courthouse and Jail of 1888.
The new facade of Saint Anthony Chapel, with its rounded arched openings and blind paneling, flanked by two great square towers, all wrought in rough-cut stone facing establishes the Romanesque style. Further indications are evidenced in the distinctive voussoirs and the carved in interlace patterns in stone above the windows and doors, the carved medallion at the center of the facade and the corbeled bracketed stonework the tops of the towers and the roof peak. The six stone pilasters that run the height of the facade suggest the masonry buttresses of the Romanesque style and the curved trefoil designs of the heavy doors flanked by two polished granite columns further define this style. Yet the extended proportions and smaller scale of the overall façade convey a lighter, less severe design, a nineteenth-century Victorian adaptation of a twelfth-century Romanesque church.
The nave of the chapel is built of brick laid three and four courses thick on a sandstone foundation. On the front facade, the brick is clad in a warm-colored sandstone. On the side walls of the addition, the brick is set in an American bond pattern, with a corbeled cornice which follows the design of the 1883 building with an additional decorative course added. The window openings are arched in finished sandstone. The roof and needle spires are of timber construction and covered in slate. The statue of St. Anthony at the roof’s front peak is a copper replacement of the original, which was toppled by lightning.