[2] The church, an imposing Gothic Revival structure built in 1866–69, was listed on the National Register of Historic Places in 1985.

The church is an imposing masonry structure, built of red brick, with sandstone trim and a slate roof.

The main façade has a central entrance recessed in a sandstone Gothic arch, with a large stained glass rose window above.

The tallest of the cathedral's three steeples is, at 204 feet (62 m)[2] Construction began in 1866 under the supervision of New York architect Patrick Keely.

Construction of the church was interrupted by Portland's great 1866 fire, and it was not completed until September 8, 1869.The cathedral has undergone restorations in 1921, 1969, and 2000.