The Federal Building and Courthouse was designed by James Knox Taylor in the early 1900s. A portion of the building was built in 1909 as the U.S. Post Office and Courthouse for San Angelo. The building was later extended in 1932 to support increased postal demands and other agency services. The building no longer serves as a postal facility, but it currently houses the U.S. Courts and other Federal agencies including the Internal Revenue Service, the Federal Probation Office, the U.S. Marshal, and the Federal Bureau of Investigation. Located in San Angelo's Central Business District, this 43,000 square foot building is situated on the corner of Twohig and Oak Street, which define the edges for the primary elevations at the northeast and the northwest. The southwest edge of the site is predominantly utilitarian and is defined by an employee parking lot and delivery drive. This drive continues ninety degrees, wrapping around the building along the southeast elevation. The rectangular brick building, built in the Renaissance Revival Style, is maintained and in good condition. Despite the twenty era difference in date of construction, the original building and its later extension present a unified appearance characteristic of the style. Some of the Italian Renaissance characteristics evident on the exterior of this building include: 1) a low pitch hipped roof 2) a rusticated ground level 3) arches above doors and first story windows 4) flat symmetrical front facades 5) upper story windows smaller and less elaborate than windows below 6) entrances accentuated by classical columns or pilasters (northwest elevation) 7) pedimented windows with a bracketed cornice, and 8) quoins at the building corners Though each elevation is unique, much of the detailing and use of architectural features is common to all. All four elevations are divided horizontally into two sections. A recessed course of brick every sixth course gives a rusticated appearance to the first floor level. The first floor is further delineated by a continuous limestone belt course that wraps around the building at the second floor line. Arched openings, detailed in tooled limestone, accentuate both entrances to the building and two windows at the main (northeast) elevation. All other first floor windows are accentuated by standard tooled limestone moldings.Some windows are further distinguished by either pediments (at the second floor above the main entrance), or a plain entablature (typical at most second floor windows, except inside the light court). All windows in this area are detailed with only the tooled limestone molding. Standing seam copper sheet metal covers the roof in a hip design. The cornice is detailed with decorative limestone mutes at the soffits and an egg and dart string course at the eaves. The interior of the building is generally organized in a U-shaped configuration about the second floor courtroom. Stairs are located at either end of the building. The primary stair in the northeast lobby rises continuously between the first and third floors. The elevator is also located in this part of the lobby. Stairs to the basement are accessible from a door inside the northeast vestibule. Stairs at the southwest end of the building connect the second and third floors only. Areas of particular significance on the interior include the fist floor lobby, main staircase, second floor courtroom, and second and third floor corridors. Notable finishes in these areas typically include terrazzo and marble floors, plaster walls, marble and wood base, molded plaster ceilings, original bronze light fixtures, and wood trim at doors and windows. The tenant spaces also retain much of their original character. The predominant presence of wood detailing and plaster finishes enhances these areas and exhibits the integrity of a typical 1930s office. Public restrooms are also original except those on the first floor. More contemporary finishes that have been selectively incorporated throughout the building include carpeting, acoustical ceiling tiles, fluorescent lighting, drywall and vinyl and ceramic floor tiles.