During the early 1930s, the National Capital Park and Planning Commission sought to develop the section of the District of Columbia known as Foggy Bottom, located between C, E, Eighteenth, and Twenty-third streets.

It was always intended to construct the building in two phases, and the Foggy Bottom site was chosen because it was large enough to accommodate both.

Gilbert Stanley Underwood and William Dewey Foster won the contract for the War Department building.

[4][5] During the design process, several agencies expressed concern that the War Department had already expanded beyond the capacity of the building.

Congress appropriated funds for construction of the Pentagon early in 1941, the same year the first phase of the building was completed.

Department of State also grew rapidly during the war (from under 1000 employees to over 7000), but was lower in priority and so got scattered all over Washington, occupying 47 buildings by the mid-1940s.

The addition was privately funded by the Diplomacy Center Foundation, a nonprofit established by former secretary of state Madeleine Albright in 2000 to honor American diplomats.

However, most of the contract would focus on replacing the building's electrical, elevator, mechanical, plumbing, and telecommunication systems.

The east entrance is inspired by the main building of the Sapienza University of Rome campus, designed by italian architect Marcello Piacentini and completed in 1935.

At either side of the forecourt, a limestone belt course runs the full width of the elevation above the basement and second stories.

The East Lobby of the original building is a two-story rectangular space surrounded by a screen of paired piers.

In the lobby of the fifth floor executive office suite is a mural by James McCreery entitled Liberty or Death: Don't Tread on Me.

The east side of the corridor includes office suites originally designated for the secretary of war and chief of staff.

The south courtyard of the State Department Building features a sculpture by Marshall Fredericks titled The Expanding Universe, which includes a circular fountain and an architectural bronze statue.

Diplomatic reception rooms were installed on the eighth floor during the 1980s as reproductions of early American architecture.