During his three-year tenure (1884–86),[2] Mifflin E. Bell, supervising architect of the U.S. Treasury Department, designed the building in the Romanesque Revival style of architecture.

In 1930, the Office of the Supervising Architect under James A. Wetmore, designed a compatible addition in a similar style, which was completed in 1933.

[4] Between 2010 and 2013 the U.S. General Services Administration (GSA) oversaw the substantial exterior restoration of the Courthouse, to protect the award-winning interior renovation.

SUPERSTRUCTURES Engineers + Architects provided commissioning services, which involved individually tracking each element of the building envelope during construction.

[7] The building is an excellent example of Romanesque Revival architecture and is a prominent component of the Municipal Center complex.

Round arches of polished granite, which feature rosettes and cable moldings, dominate the first story.

Arched openings with semi-circular balconies are topped by an ornate cornice surmounted by a steeply pitched pyramidal roof.

Each level of the loggia is supported by cast-iron columns that are adorned with acanthus and anthemion leaf motifs.

Large round-arch windows have carved wood mullions and are operated by cast-metal pulls with griffin-head motifs.

During World War II, a skylight and laylight that originally illuminated the postal work floor were covered to comply with black-out laws implemented to protect the country from enemy bombings.

A U-shaped green-glass and aluminum curtain wall was added to the 1933 portion of the building in 2003, forming an interior atrium that, along with new skylights, admits natural light.

GSA also refurbished interior stone, metal, plaster, and wood finishes; restored historic windows and doors; and added three new courtrooms.

On the exterior, the cast-iron roof cresting was repaired and historically appropriate street-lights were installed on the site.