
Each street elevation features a central pavilion which in turn bears a portico. The principal facade is the southern, along Olive Street, which features an iron mansard dome.
#Architect license search for the state of missouri windows
Interior structure is a mixture of wrought and cast iron, supporting arched brick floors in a system that was referred to at the time of construction as "fireproof." The building's windows were provided with fireproof shutters. High ceilings predominate in the main structure, with first floor ceilings at 26 feet (7.9 m) and second and third floors at 22 feet (6.7 m). The building surrounds a skylit inner courtyard, 48 feet (15 m) by 55 feet (17 m). The basement material is red Missouri granite, while the upper floors are gray granite from Hurricane Island, Maine, between 3 feet (0.91 m) and 4 feet (1.2 m) in thickness. The basement connects to a tunnel under 8th Street that was used for the delivery of mail to the post office. It includes a basement, sub-basement and attic level, with 16-foot (4.9 m) ceilings at the basement levels and 10-foot (3.0 m) thick foundation walls, which are surrounded by a 25-foot (7.6 m) deep dry moat for light and ventilation.

The three-story monumental granite building is 234 feet (71 m) long and 179 feet (55 m) deep. Mullett's other Second Empire buildings in Boston, Cincinnati, New York City and Philadelphia have been demolished. It is in the Second Empire architectural style popular in the post Civil-War era. The others are the Eisenhower Executive Office Building in Washington, D.C., the Century Post Office in Raleigh, N.C. Located at the intersection of Eighth and Olive Streets, it is one of four surviving Federal office buildings designed by Mullett. Mullett, William Appleton Potter, and James G.

Custom House and Post Office is a court house at 815 Olive Street in downtown St.
