This Gothic Revival Roman Catholic church is highly visible thanks to its bulk, the vigorous coloring of its materials, and its location on the high spine of the old Washington Pike. It is the latest, and best, of a trio of churches built along the former pike during the interwar years. The others are the rock-faced Gothic Revival Mt. Lebanon United Methodist Church of 1923 by Charles Bier (3319 W. Liberty Avenue) and the twin-towered Gothic Revival Mt. Lebanon United Presbyterian Church (255 Washington Avenue) designed by J. Lewis Beatty in 1929. William Perry designed numerous churches and schools in western Pennsylvania and the Midwest. The most visible of Perry's local works today are this church and the former St. Philomena Church and School (now the Community Day School) of 1922 at 6424 Forward Avenue in Squirrel Hill.
St. Bernard's is constructed of coursed but rough-faced stones that range in color from gray to brown and red. Its interior is magnificent, thanks to Perry's firsthand knowledge of medieval architecture in southern France and Catalonia in northeastern Spain. Diaphragm arches in stone set up a rhythm along the wooden roof, and a ribbed dome covers the sanctuary. Especially impressive are the murals by Jan Henryk de Rosen that adorn the church and that include scenes from the New Testament and the life of St. Bernard. The church's capitals are by Frank Aretz, and the stained glass is by Alfred Fisher in the main church and by A. Leo Pitassi in the lower church.