Chicago Federal Center Plaza, also known as Chicago Federal Plaza, unified three buildings of varying scales: the mid-rise Everett McKinley Dirksen Building, the high-rise John C. Kluczynski Building, and the single-story Post Office building. The complex’s plot area extends over two blocks; a one-block site, bounded by Jackson, Clark, Adams, and Dearborn streets, contains the Kluczynski Federal Building and U.S. Post Office Loop Station, while a parcel on an adjacent block to the east contains the Dirksen U.S. Courthouse. The structural framing of the buildings is formed of high-tensile bolted steel and concrete. The exterior curtain walls are defined by projecting steel I-beam mullions covered with flat black graphite paint, characteristic of Mies's designs. The balance of the curtain walls are of bronze-tinted glass panes, framed in shiny aluminum, and separated by steel spandrels, also covered with flat black graphite paint. The entire complex is organized on a 28-foot grid pattern subdivided into six 4-foot, 8-inch modules. This pattern extends from the granite-paved plaza into the ground-floor lobbies of the two tower buildings with the grid lines continuing vertically up the buildings and integrating each component of the complex. Associated Architects that have played a role in the complex’s long history from 1959 to 1974 include Schmidt, Garden & Erickson; C.F. Murphy Associates; and A. Epstein & Sons.