The President's Room is one of the most ornate rooms in the United States Capitol, richly adorned with fresco paintings by Greek-Italian artist Constantino Brumidi. The room was completed in 1859 as part of the Capitol's vast extension, which added new Senate and House wings and the new cast-iron dome. The President's Room is room number S-216.

When architects designed the new Senate wing in the early 1850s, senators directed them to include a President's Room, partly to symbolize the Senate's constitutional responsibility to provide the President of the United States with advice and consent on nominations and treaties. Presidents used the room to sign legislation into law at the close of each session of Congress. This practice ended in 1933 with the ratification of the Twentieth Amendment to the United States Constitution, which established different ending dates for presidential and congressional terms of office. Although occasionally used by presidents, the room today is utilized primarily by senators for interviews and press conferences.

In 1991, the room's historic furnishings were restored to the 1870s period by the Senate Commission on Art. The ceiling and walls were also restored to their original glowing colors and subtle details, and the mirrors were regilded. The room is only accessible on a guided tour with a Congressional staff member when the Senate is not in session.

During the impeachment trial of Bill Clinton, Chief Justice William Rehnquist used the President's Room as an office. Chief Justice John Roberts used the room as an office during the first impeachment trial of Donald Trump.

The room was first used by President James Buchanan on March 4, 1861, at a time of great peril for the nation, after several southern states had left the Union and a month before the Civil War began. The country was still at war on March 3, 1865, when President Abraham Lincoln visited the President's Room to sign the usual flurry of end-of-session legislation. There he received word from Union General Ulysses S. Grant that Confederate General Robert E. Lee had requested a meeting to discuss "the subjects of controversy between the belligerents."

After consulting with Secretary of War Edwin M. Stanton and Secretary of State William Henry Seward, Lincoln responded through Stanton that Grant was not to confer with the Confederate general, "unless it be for the capitulation of General Lee's army," but should "press to the utmost your military advantages."

Lee surrendered the Army of Northern Virginia to Grant the following month. A dozen years later, on March 3, 1877, President Grant used the President's Room to sign legislation enacted during the final days of the Forty-fourth Congress.

Woodrow Wilson had great plans for this room when he became president in 1913. The first Democratic president in sixteen years, he intended to use the President's Room as a working office to confer with congressional Democrats, who controlled both houses for the first time in eighteen years. At first, Wilson was a frequent caller, but he visited the Capitol less often as support for his legislative agenda faltered and his relations with Congress deteriorated. Republicans, who regained the Senate majority in 1918, resented Wilson's failure to confer with the Senate before negotiating the treaty ending World War I, as did many members of Wilson's own party, and the President suffered a humiliating defeat when the Senate rejected the Versailles Treaty on November 19, 1919, and again on March 19, 1920.