The Federal Building in Columbia, South Carolina was built in 1936 and is of the Renaissance Revival style. The building consists of a basement, first, second, and third stories, a partial fourth level on the east and west sides and a partial fifth story with mirador rising from the center of the building. The building is of concrete and masonry construction, with steel and wood roof framing. The exterior walls and trim are all concrete. The building features a rusticated base, rusticated quoins, smooth walls and trabeated fenestration accented with various types of pediments.
The Federal Building derives much of its significance from the method of construction. The building was constructed of poured monolithic concrete. It was the first building to be constructed this way in South Carolina and one of the first in the country to utilize this method of construction.
The front facade is divided into five bays. The central pavilion projects beyond the plane of the facade. It is detailed with six Ionic fluted pilasters which define five bays within the central pavilion. The pilasters support the unenriched entablature and a pediment. The central pavilion divides the front facade into two wings (east and west). The entrance is in the central portion of the building. It consists of three recessed arched openings defined by rusticated voussoirs. Each opening contains a decorative wood fan light. The original wood doors have been replaced with steel ones but the contemporary doors are reminiscent of the original. The concrete platform spans the width of the central pavilion of the building and supports two wrought iron lamposts. The rear facade repeats the pattern of the front.
The center portion of the building contains a rectangular plan fourth level. Crowning the fourth level is a fifth octagonal level which formerly housed a weather station and an observatory tower (the mirador).
The two side facades are divided into five bays with the central bays defined by engaged pilasters of the Tuscan order. The window heads are more pronounced than those at the front and rear.
The fenestration varies at each level. At the first level the windows are eight over eight, double hung, set in a rusticated facade with radiating rusticated voussoirs. The second level openings are detailed with simple molded surrounds except at the central pavilion where the center opening has a broken scroll pediment while the flanking apertures have plain pediments. The center window openings of each end pavilion are detailed with segmented arched pediments and ancons. At the third level, the windows are eight over eight double hung except for the central pavilion where they are twelve over twelve. All the fenestration on the rear (south) facade repeats the pattern of the front except at the third level where the windows are blocked-in at the south side of the courtroom.
The interior of the building has had some alteration since construction. Its most notable feature is the third floor courtroom which appears to be in almost original condition.