The Federal Building and Post Office constructed in the Modern style is a five story plus a basement masonry structure. The exterior walls are clad with blonde brick between vertical, white, precast concrete columns above a coursed ashlar granite base. The site generally retains the original layout with landscaped planting areas on the north and east sides of the site and parking lots on the south and west sides of the site.
The base of the building has a projecting granite base with a sloped top that forms the sill for the first floor windows. Vertical, white, precast concrete columns run from the top of the granite up to the precast concrete parapet cap. At twenty foot intervals, the columns consist of doubled rubs. At the first floor aluminum windows and transoms infill the space between the columns. A precast concrete band wraps the building at the level of the second floor and from that point up, the building is clad with blonde brick in a running bond pattern between concrete ribs spaced at 5’ on center between the double rib columns. A small penthouse is located on the roof and it is clad in the same materials as the main building facades. The roof is flat with built up roofing with gravel ballast. The windows are center pivot windows with milled clear aluminum frames. A one story element extends south from the tower and houses the Post Office workroom. This section of the building is clad with blonde brick with a horizontal precast concrete band that aligns with the band on the tower and a precast parapet cap.
The main (north) façade faces East Babcock Street and has ten even bays. There are two entrances on the north elevation, one for the Post Office and one for the Federal Building. The entries are offset to the west of being centered on the façade. Both are aluminum storefront entry systems that extend up to the continuous canopy that runs between them. The canopy has precast concrete and granite detailing. Below the canopy between the two entries, the façade has black granite panel cladding. Aluminum letters that say “Federal Building” above in big font with the words “United States Post Office” below in smaller front and aluminum casts of the Great Seal of the United States on either side of the letters are mounted on the granite panels.
The west façade consists of a three bay five story tower with a single bay one story element to the south of it. There is an entrance located in the middle bay that consists of a single aluminum storefront door. The penthouse is set back from the building façade but is still visible from the west. A series of narrow vertical rectangular aluminum windows on the one story element is the only interruption to the brick cladding, aside from the continuous horizontal precast concrete band.
The south façade consists of the one story portion of the building with the tower behind it. The building loading dock is located on the east end of the south façade and extends out from the one story section of the building. The loading dock is concrete with brick wing walls and a flat roof. There are three doors into the building from the loading dock. The tower has ten bays and generally matches the detailing on the north elevation. The penthouse, located at the east end of the roof, is two bays wide and is flush with the tower elevation. There are no windows in these two tower bays, instead the bays have solid brick infill between the concrete ribs since these bays contain the restrooms and stair core. The easternmost bay on the south elevation also contains a stair core so it has has solid brick infill and no windows.
The east façade has the same detailing as the west façade. The only difference is the southernmost tower bay has solid brick infill and no windows.
The majority of the interior spaces have been altered throughout the building. The most intact spaces in the building are the main entrance lobbies which still retain the original layout and some of the original finishes including the terrazzo flooring and marble wall panels. The Federal Building lobby is very intact with the original acoustic tile ceiling finish and light fixtures and no alterations to the layout. The Post Office lobby has been somewhat altered and has new interior walls with new Post Office boxes and service counters and a modern acoustic tile ceiling.
The restrooms have generally retained the original layout and finishes, though most restrooms have undergone minor alterations for accessibility. The floor and walls have ceramic tile finishes and the ceilings are plaster with recessed light fixtures. The third floor restrooms were completely remodeled, though the size and shape are similar the original ceramic tile finishes on the walls and floor but not the same colors. The corridors around the elevator core generally retain the original layout but the finishes are all new.