The United States Treasury Department sought designs for the new federal building from private architectural firms through an open competition allowed under the Act.

[4] The south (front) elevation has eleven bays, separated by three-story Ionic engaged columns and flanked by entry pavilions.

Each pavilion has a central cast-bronze and glass doorway, reached by a wide, shallow gray granite stair flanked by pedestals with heroic allegorical sculptures by John Massey Rhind entitled Industry, Science (or Justice[5]), Agriculture, and Literature.

The addition is compatible with the original building, featuring classical ornamentation mixed with modern details such as the stylized relief over the entrances.

The major interior spaces of the building are the first-floor lobbies and connecting corridor and the original courtrooms at the southeast and southwest corners of the second floor.

The corridors lead to vaulted octagonal vestibules that feature red marble walls and gray Tuscan columns, as well as Roman-style mosaics on the ceilings.

Arched openings of the octagonal vestibules lead to lobbies with elevators and grand staircases, and to the four-part vaulted connecting corridor.

In recent years, the General Services Administration (GSA) has reversed some past modifications made in the name of modernization, and has begun conserving important elements of the building.

GSA has replaced modern lighting with appropriate period features, repaired mosaic tile ceilings, and restored exterior stonework.