Designed in the Greek Revival style[4][5][2] by architect Robert Mills, construction started in 1836, and the massive structure took 31 years to complete.

In Pierre (Peter) Charles L'Enfant's plan for the capital city, the site of the Patent Office Building, halfway between the Capitol and the President's House, was set aside for a monumental structure.

[7][8] Mills described the proportions of the Greek Revival central portico as "exactly those of the Parthenon of Athens", a departure in Washington, where previously ambitious public buildings had been based on Roman and Renaissance precedents.

Fireproofing the design was an essential concern: Mills spanned the interior spaces with masonry vaulting without the use of wooden beams.

[10] From 1854 to 1857, Clara Barton worked in the building as a clerk to the Patent Commissioner, the first woman federal employee to receive equal pay.

Wounded soldiers lay on cots in second-floor galleries, among glass cases holding models of inventions that had been submitted with patent applications.

The American poet Walt Whitman frequented "that noblest of Washington buildings"[11] and read to wounded men.

Whitman worked at the Bureau of Indian Affairs, located in the building, from January 24 to June 30, 1865, before being fired for having a copy of Leaves of Grass in his desk.

The Faulkner, Kingsbury & Stenhouse firm of architects supervised the renovation of the interior as museum space starting in 1964.

The roof leaked; netting had to be placed in some galleries to catch falling ceiling plaster; window frames were rotting; the floor tiles in the Great Hall were crumbling, and the exterior façade was so degraded it was shedding fist-sized pieces of rock.

[17] The 2000 to 2006 renovation included restoring the porticos modeled after the Parthenon in Athens, a curving double staircase, colonnades, vaulted galleries, large windows, and skylights as long as a city block.

That month, Nan Tucker McEvoy (a California newspaper heiress and arts patron) donated $10 million for the renovation.

Smithsonian officials subsequently began discussing a major change to the renovation design: Adding a glass roof to the open courtyard in the center of the Old Patent Office Building.

[26] In November 2004, Robert Kogod (a real estate development executive) and his wife, Arlene (heir to Charles E. Smith Construction fortune) donated $25 million to complete the canopy.

NCPC officials said they were convinced by the concerns raised by preservationists, and condemned the Smithsonian's design approval process for being exclusionary.

[30] Washington Post architectural critic Benjamin Forgey described the changes as "relatively minor adjustments" and "pretty much the very same design".

[21] In October 2005, the Donald W. Reynolds Foundation made another major gift, donating $45 million to finish both the building renovation and the canopy manufacture and installation (now scheduled to be complete in July 2007 or later).

The Smithsonian said it would call its conservation laboratory the Lunder Conservation Center after receiving a $5.7 million grant from the Harold Alfond Foundation, name the new 356-seat underground auditorium after Nan Tucker McEvoy; designate the courtyard the Robert and Arlene Kogod Courtyard; and name its "open storage" facility the Luce Foundation Center.

In 2007, following its conclusion, Washington Post critic Philip Kennicott called the courtyard a "compelling and peaceful public space".

He concluded, "Now that it's finished, it's unfortunate that the canopy isn't more visible from the outside (you need to be above street level, in an adjacent building, to see it clearly, and it can be glimpsed peeking above the roofline if seen from a few blocks away).