[12] L'Enfant secured the lease of quarries at Wigginton Island and along Aquia Creek in Virginia for use in the foundations and outer walls of the Capitol in November 1791.

At least ten individuals submitted designs for the Capitol; however the drawings were regarded as crude and amateurish, reflecting the level of architectural skill present in the United States at the time.

[22] In an effort to console Hallet, the commissioners appointed him to review Thornton's plans, develop cost estimates, and serve as superintendent of construction.

[26] The current cast-iron dome and the House's new southern extension and Senate new northern wing were designed by Thomas Ustick Walter and August Schoenborn, a German immigrant, in the 1850s,[27] and were completed under the supervision of Edward Clark.

Despite the wishes of Jefferson and the President, Hallet went ahead anyway and modified Thornton's design for the East Front and created a square central court that projected from the center, with flanking wings which would house the legislative bodies.

[31] In March 1803, James Madison appointed Benjamin Henry Latrobe to the position of "Surveyor of Public Buildings", with the principal responsibility of completing construction of the Capitol's south and north wings.

[32] For several decades, beginning when the federal government moved to Washington in the fall of 1800, the Capitol building was used for Sunday religious services as well as for governmental functions.

According to the U.S. Library of Congress exhibit Religion and the Founding of the American Republic: It is no exaggeration to say that on Sundays in Washington during the administrations of Thomas Jefferson (1801–1809) and of James Madison (1809–1817) the state became the church.

As early as January 1806 a female evangelist, Dorothy Ripley, delivered a camp meeting-style exhortation in the House to Jefferson, Vice President Aaron Burr, and a "crowded audience".

Construction continued through to 1826, with the addition of the center section with front steps and columned portico and an interior Rotunda rising above the first low dome of the Capitol.

Latrobe is principally connected with the original construction and many innovative interior features; his successor Bulfinch also played a major role, such as design of the first low dome covered in copper.

[36] The 1850 expansion more than doubled the length of the United States Capitol; it dwarfed the original, timber-framed, copper-sheeted, low dome of 1818, designed by Charles Bulfinch which was no longer in proportion with the increased size of the building.

[41] When the Capitol's new dome was finally completed, its massive visual weight, in turn, overpowered the proportions of the columns of the East Portico, built in 1828.

[45] The same year, the power plant was renovated and expanded in accordance with legislation passed in 1970, and the stones fell to the Commission on the Extension of the United States Capitol.

[52] The Capitol draws heavily from other notable buildings, especially churches and landmarks in Europe, including the dome of St. Peter's Basilica in the Vatican and St. Paul's Cathedral in London.

[56] As of 2012, $20 million in work around the skirt of the dome had been completed, but other deterioration, including at least 1,300 cracks in the brittle iron that have led to rusting and seepage inside, needed to be addressed.

The frieze is located around the inside of the base of the dome and is a chronological, pictorial history of the United States from the landing of Christopher Columbus to the Wright Brothers's flight in Kitty Hawk, North Carolina.

Trumbull was a contemporary of the United States' founding fathers and a participant in the American Revolutionary War; he painted a self-portrait into Surrender of Lord Cornwallis.

First Reading of the Emancipation Proclamation of President Lincoln, an 1864 painting by Francis Bicknell Carpenter, hangs over the west staircase in the Senate wing.

[64] The Capitol also houses the National Statuary Hall Collection, comprising two statues donated by each of the fifty states to honor persons notable in their histories.

The statue's extraordinary weight of 15,000 pounds (6,800 kg) raised concerns that it might come crashing through the floor, so it was moved to Emancipation Hall of the new Capitol Visitor Center.

[70] The chamber is large enough to accommodate members of all three branches of the federal government and invited guests for joint sessions of Congress such as the State of the Union speech and other events.

Of the twenty-three relief portraits, only Moses is sculpted from a full front view and is located across from the dais where the Speaker of the House ceremonially sits.

In 1875, as one of his first recommendations, Olmsted proposed the construction of the marble terraces on the north, west, and south sides of the building creating an enveloping base.

This addressed issues with the placement of the original structure; it had been built too far westwards on the crest of the hill and gave the appearance as if the building might slide into the marshy terrain below.

[citation needed] Constituents pay for U.S. flags flown over the Capitol to commemorate a variety of events such as the death of a veteran family member.

The general public has paid respect to a number of individuals lying in state at the Capitol, including numerous former presidents, senators, and other officials.

On the checkpoints at the shorter cross streets, the barriers are typically kept in a permanent "emergency" position, and only vehicles with special permits are allowed to pass.

Structures ranging from scores of Jersey barriers to hundreds of ornamental bollards have been erected to obstruct the path of any vehicles that might stray from the designated roadways.

[102][103] The complex contains 580,000 square feet (54,000 m2) of space below ground on three floors,[104] and offers visitors a food court, restrooms, and educational exhibits, including an 11-foot scale model of the Capitol dome.