The Old Post Office, also known as the former Pekin Federal Building, is a historic building in Pekin, Illinois. Built in 1906, the building held Pekin's U.S. government offices; the first floor served as the city's main post office, while the second floor held various offices, including a Department of the Treasury office and an Army recruitment office. Supervising Architect James Knox Taylor designed the building in the Renaissance Revival style, in keeping with the tradition of using classical styles for federal buildings. The building's design features a red brick exterior with a limestone base and quoins; fanlights and keystones above the first-floor windows; and a limestone cornice with a parapet wall and a cartouche above the main entrance.