The Federal Building and United States Courthouse is a four story white marble building in the Classical Revival style. It occupies an entire block on 5th Avenue, between 18th and 19th Streets in the Central Business District of downtown Birmingham.
The original building (1921) was two stories high, above a full basement. In the later 1930's a two story addition was constructed appearing as a third level and an attic below a hipped roof. The main facade (south) includes a central colonnade flanked on either side by a projecting entrance pavilion and wing. The wings extend rearward so that the mass of the building creates a U-shaped plan.
The central colonnade of the south (front) façade is composed of fourteen free-standing Ionic columns. Each bay between the columns contains an arched window at the first floor. The colonnade supports an entablature with an unadorned architrave and denticulated cornice, which continues around the south, east and west elevations. A marble balustrade above the entablature masks the third floor setback above the colonnade. The projecting entry pavilions flank the central colonnade. Each entry is approached by a broad flight of granite steps flanked by marble cheek walls with original cast bronze light standards, now painted. The arched main entries are delineated by engaged Ionic columns which support the entablature above the second floor level.
The east (side) facade is composed of a five bay colonnade at the center with flanking three bay pavilions. Six engaged Ionic columns comprise the colonnade, which is flanked by rectangular piers. The projections flanking the central recessed east pavilion are three bays wide. Copper clad dormers emerge from the roof - one over each end pavilion, and three over the center. Two bronze and glass entry doors appear at the head of short flights of steps at the northeast and southeast corners. The doors are set within an arched opening and are surmounted by nine-light arched windows. Ornamental painted bronze, lantern-style wall-mounted fixtures flank each door.
The west (side) elevation is similar to the east, except that a slate shingled penthouse in the form of a flat-roofed shed dormer appears on the roof of this elevation. There is one arched entryway at the northwest corner. At the center of the elevation, marble steps lead down to a basement entry (now closed).
The building site is surrounded on the south, east and west sides by a massive marble balustrade. Marble clad walls off the balustrade open onto the entries. The landscaping is dominated by magnolia trees at the south, east and west elevations.
The north elevation contains the original loading dock area. The detailing of the east and west elevations continues at the north elevation of the east and west wings and wraps the first three bays of the light court. The walls of the light court are buff colored brick. The openings of the original loading dock have been infilled and finished with stucco, now appearing as blind openings. The central projecting covered portion of the original loading dock remains open and is used for parking and as a secured entry.
Significant interior spaces include the marble finished lobby with bronze elevator doors and grand marble staircases at each end; marble elevator lobbies and corridors at second and third floors; and a ceremonial courtroom on the third floor which features full-height wood paneling.