United States Post Office and Courthouse, Federal building in downtown Dallas, United States.

The United States Post Office and Courthouse at 400 North Ervay Street in downtown Dallas is a five-story, steel-framed building clad in Indiana limestone in the Renaissance Revival style used by the U.S. Treasury Department. It spans the length of Bryan Street, with colored terra cotta spandrels on the upper floors depicting the history of mail transportation. A post office still operates on the ground level, and the upper floors hold 78 apartments.

The building opened in 1930 as a federal center housing numerous government agencies and two courts under one roof. A major renovation completed in 2011 transformed the upper floors into residential apartments while keeping the post office operational below.

Above the two entrance doorways, the lobby carries regional murals; on the upper floors, colored terra cotta spandrels picture the history of mail transportation. The building's name is often shortened to the old Dallas post office and courthouse, and the ground-floor post office still serves customers.

The building occupies the block bounded by Ervay, Federal, St. Paul and Bryan streets at 400 North Ervay Street, in the City Center District of downtown Dallas. The post office on the ground level stays open to the public, while the 78 apartments on the upper floors are private. Renovation work added a basement parking facility and brought the structure into line with ADA accessibility criteria.

The steel-framed structure uses Indiana limestone as cladding, a material specifically favored for federal buildings of that era. The window stations in the main lobby still display the original configuration and design from the 1930s.