The building was originally designed by William Thornton. This plan was subsequently modified by Stephen Hallet, Benjamin Latrobe and then Charles Bulfinch. The current dome and the House and Senate wings were designed by Thomas U. Walter and August Schoenborn, a German immigrant, and were completed under the supervision of Edward Clark.
The building is marked by its central dome above a rotunda and two wings, one for each chamber of Congress: the north wing is the Senate chamber and the south wing is the House of Representatives chamber. Above these chambers are galleries where visitors can watch the Senate and House of Representatives. It is an example of the Neoclassical architecture style. The statue on top of the dome is the Statue of Freedom.
Underground tunnels (and even a private underground railway) connect the main Capitol building with each of the Congressional office buildings in the surrounding complex. All rooms in the Capitol are designated as either S (for Senate) or H (for House), depending on whether they are north (Senate) or south (House) of the Rotunda. Similarly, rooms in the Congressional office buildings are designated as HOB (for House Office Building, which are all south of the Capitol) or SOB (for Senate Office Building, which are all north of the Capitol). Additionally, all addresses in Washington, D. C. are designated NE, NW, SE, or SW, in relationship to the Rotunda. (Since the Capitol Rotunda is not located in the center of the District — it is slightly farther east and south — the four D.C. quadrants are not the same shape and size.)
In 1792, a contest was announced by Commissioners of the Federal City seeking designs for both the Congress House and the President's House. The contest deadline was July 15, 1792, with rewards including $500 and a lot in the city. All the drawings submitted were considered inadequate and rejected. The most promising of the submissions was by Stephen Hallet. However, a late entry by amateur architect William Thornton was submitted on January 31, 1793 to much praise by President George Washington and Secretary of State Thomas Jefferson. Thornton was inspired by the east front of the Louvre, as well as the Pantheon for the center portion of the design. Thornton's design was officially approved in a letter, dated April 5, 1793, from George Washington. In effort to console Hallet, the commissioners appointed him to review Thornton's plans, develop cost estimates, and serve as superintendent of construction. Hallet proceeded to pick apart and make drastic changes to Thornton's design, which he saw as amateur with numerous problems and high costs to build. Jefferson appointed a five-member commission, including Hallet and James Hoban, to address problems with and revise Thornton's plan. Except for some details in Thornton's plan that specified an open recess in the center of the East front, the revised plan was accepted.
Adorned in masonic attire, George Washington laid the cornerstone on September 18, 1793 during a groundbreaking ceremony for construction of the Capitol. The stone is located near the Old Supreme Court, through a passageway taken by people visiting the United States Senate Gallery. It is not known that this actually is the original cornerstone, but it was engraved with a masonic symbol and commissioned in 1893 (100 years after its placement). The cornerstone has been moved from its original location.
Construction proceeded with Hallet working under supervision of James Hoban, who was also busy working on construction of the White House. 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. Hallet was dismissed by Jefferson on November 15, 1794. George Hadfield was hired on October 15, 1795 as superintendent of construction, but resigned three years later in May 1798, due to dissatisfaction with Thornton's plan and quality of work done thus far.
The Senate wing was completed in 1800, while the House wing was completed in 1811. However, the House of Representatives moved into the House wing in 1807. Though the building was incomplete, the Capitol held its first session of United States Congress on November 17, 1800. The legislature was moved to Washington prematurely, at the urging of President John Adams in hopes of securing enough Southern votes to be re-elected for a second term as president.
The Capitol was built and later expanded in the 1850s using the labor of slaves "who cut the logs, laid the stones and baked the bricks". The original plan was to use workers brought in from Europe; however, there was a poor response to recruitment efforts, and African Americans—free and slave—composed the majority of the work force. The Statue of Freedom on top of the dome was completed in 1863. The Supreme Court also met in the Capitol until its own building (behind the East Front) was completed in 1935.
When the dome of the Capitol was finally completed, it was significantly larger than the original plan, and its massive visual weight overpowered the proportions of the columns of the East Portico, built in 1828. The East Front of the Capitol building was rebuilt in 1904, following a design of the architects Carrère and Hastings, who also designed the Senate and House office buildings. A marble duplicate of the sandstone East Front was built 33.5 feet (10.2 m) from the old Front during 1958-1962, and a connecting extension incorporated what formerly was an outside wall as an inside wall. In the process, the Corinthian columns were removed, and landscape designer Russell Page created a suitable setting for them in a large meadow at the National Arboretum, where they are combined with a reflecting pool in an ensemble that reminds some visitors of Persepolis.
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, St. Paul's Cathedral in London and Saint Isaac's Cathedral in Saint Petersburg. On the roofs of the Senate and House Chambers are flagpoles that fly the U.S. flag when either is in session.
On June 20, 2000, ground was broken for the Capitol Visitor Center, which is due to open in December 2008. Since 2001, the East Front of the Capitol (site of most Presidential Inaugurations until Ronald Reagan broke tradition in 1981) has been the site of construction for this massive underground complex, designed to facilitate a more orderly entrance for visitors to the Capitol. (When construction is complete, the East Front will be restored to its earlier, pre-pavement appearance.) Prior to the center being built, visitors to the Capitol had to queue on the parking lot and ascend the stairs, whereupon entry was made through the massive sculpted Columbus Doors, through a small narthex (with cramped security) and thence directly into the Rotunda. The new underground facility will provide a grand entrance hall, a visitors theater, room for exhibits, and dining and restroom facilities, in addition to space for building necessities such as an underground service tunnel. Some people, however, lament the loss of the ability of the common person to walk right into the Capitol.
Olmstead also designed the Summer House, the open-air brick building that sits just north of the Capitol. Three arches open into the hexagonal structure, which encloses a fountain and twenty-two brick chairs. A fourth wall holds a small window that looks onto an artificial grotto. Built between 1879 and 1881, the Summer House was intended to answer complaints that visitors to the Capitol had no place to sit and no place to obtain water for their horses and themselves. Modern drinking fountains have since replaced Olmsted's fountain for the latter purpose. Olmsted intended to build a second, matching Summer House on the southern side of the Capitol, but Congressional objections led to the project's cancellation.
The Capitol has a long history in art of the United States, beginning in 1856 with Italian-American artist Constantino Brumidi and his murals in the hallways of the first floor of the Senate side of the Capitol. The murals, known as the Brumidi Corridors, reflect great moments and people in United States history. Among the original works are those depicting Benjamin Franklin, John Fitch, Robert Fulton, and events such as the Cession of Louisiana. Also decorating the walls are animals, insects and natural flora indigenous to the United States. Brumidi's design left many spaces open so that future events in United States history could be added. Among those added are the Spirit of St. Louis, the Moon landing, and the Challenger shuttle crew. Brumidi also worked within the Capitol Rotunda. He is responsible for the painting of The Apotheosis of Washington beneath the top of the dome, and also the famous Frieze of United States History. The Apotheosis of Washington was completed in 11 months and painted by Brumidi while suspended nearly 180 feet (55 m) in the air. It is said to be the first attempt by the United States to deify a founding father. Washington is depicted surrounded by 13 maidens in an inner ring with many Greek and Roman gods and goddesses below him in a second ring. 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. The frieze was started in 1878 and was not completed until 1953. The frieze was therefore painted by four different artists: Brumidi, Filippo Costaggini, Charles Ayer Whipple, and Allyn Cox. The final scenes depicted in the fresco had not yet occurred when Brumidi began his Frieze of the United States History.
Within the Rotunda is also located eight paintings of the development of the United States as a nation. On the east side are four paintings depicting major events in the discovery of America. On the west are four paintings depicting the founding of the United States. The east side paintings include The Baptism of Pocahontas by John Gadsby Chapman, The Embarkation of the Pilgrims by Robert W. Weir, The Discovery of the Mississippi by William H. Powell, and The Landing of Columbus by John Vanderlyn. On the west side is The Declaration of Independence, The Surrender of General Burgoyne, The Surrender of Lord Cornwallis, and General George Washington Resigning His Commission, all painted by John Trumbull, a contemporary of United State's founding fathers and a participant in the U.S. Revolutionary War. In fact, Trumbull painted himself into The Surrender of Lord Cornwallis.
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. One of the most notable statues in the National Statuary Hall is a bronze statue of King Kamehameha donated by the state of Hawaii upon its accession to the union in 1959. The statue's extraordinary weight of 15,000 pounds raised concerns that it might come crashing through the floor, so it was moved to a position in the Hall which could withstand the weight load. The 100th, and last statue for the collection, that of Po'pay from the state of New Mexico, was added on September 22, 2005. Po'pay was the first statue moved to and now resides in Emancipation Hall of the new Capital Visitor's Center.
Eleven other presidents have lain in state in the Rotunda for public viewing, most recently Gerald Ford. The tomb meant for Washington now stores the catafalque which is used to support caskets lying in state or honor in the Capitol. After the Capitol Visitors Center is completed, the catafalque will be on display for the general public to see when not in use.
In the basement of the Capitol building in a utility room are two marble bathtubs, which are all that remain of the once elaborate Senate baths. These baths were a spa-like facility designed for members of Congress and their guests before many buildings in the city had modern plumbing. The facilities included several bathtubs, a barbershop, and a massage parlor.
There are also 365 steps leading up to the West Front of the Capitol Building, each representing a day in the year.
The House of Representatives Chamber is adorned with relief portraits of famous lawmakers and lawgivers throughout history.
In order clockwise around the chamber:
The Senate Chamber is adorned with white marble busts of the former Presidents of the Senate (Vice Presidents).
From 1800 to 1806 this room served as the Senate Chamber and from 1806 until 1860, the room was used as the Supreme Court Chamber. In 1860, the Supreme Court began using the newly vacated Old Senate Chamber. Since 1935, the Supreme Court has met in the US Supreme Court building.
The Capitol, as well as the grounds of Capitol Hill, have played host to major events. Among the major events the Capitol has hosted:
On July 2, 1915, prior to the United States' entry into World War I, Frank Holt (a.k.a. Eric Muenter), a German professor who wanted to stop American support of the Allies in World War I, exploded a bomb in the reception room of the U.S. Senate. The next morning he tried to assassinate J.P. Morgan, Jr., son of the financier, at his home on Long Island. In a letter to the Washington Evening Star published after the blast, Muenter writing under an assumed name, said he hoped that the detonation would “make enough noise to be heard above the voices that clamor for war” J.P. Morgan’s company served as Great Britain’s principal U.S. purchasing agent for munitions and other war supplies.
In 1954, Puerto Rican nationalists opened fire on members of Congress from the visitors gallery.
On March 1, 1971, a bomb exploded on the ground floor of the Capitol, placed by the New Left group, the Weather Underground or Weathermen. They placed the bomb as a demonstration against U.S. involvement in Laos.
On November 7, 1983, a group called the Armed Resistance Unit claimed responsibility for a bomb that detonated in the lobby outside the office of Senate Minority Leader Robert Byrd. Six people associated with the John Brown Anti-Klan Committee were later found in contempt of court for refusing to testify about the bombing. In 1990 three members of the Armed Resistance Unit were convicted of the bombing, which they claimed was in response to the invasion of Grenada.
The Capitol building is believed to have been the intended target of the hijacked United Airlines Flight 93 on September 11, 2001, before it crashed in Somerset County, Pennsylvania after passengers tried to take over control of the plane from hijackers. Since the September 11, 2001 attacks, the roads and grounds around the U.S. Capitol Building have undergone dramatic changes.
On June 9, 2004, while en route to memorial services for former president Ronald Reagan, Kentucky Governor Ernie Fletcher's plane inadvertently caused a security scare. It caused the Capitol to be evacuated, because the transponder of the plane failed while flying in restricted airspace above the Capitol. The security scare happened just moments before the plane with Reagan's body touched down at Andrews Air Force Base.
Construction is well underway on an underground, 3-level, United States Capitol Visitor Center by the east face of the Capitol. The estimated final cost as of March 2007 is about $600 million. The project had long been in the planning stages, but the attacks provided the impetus to start work. Construction began in the fall of 2001. Security is expected to be enhanced by directing all public visitors through the center. Critics say that security improvements have been the least of the project's expense; indeed, construction delays and added features by Congress continue to add to the cost. Citizens Against Government Waste have called it a Monument to Waste. However many, including those who work in the Capitol, consider it a necessary and appropriate historical project. It will be mainly underground, though skylights will provide views of the Capitol dome.
The United States Capitol Police have also installed checkpoints to inspect vehicles at specific locations around Capitol Hill, and have closed a section of one street indefinitely. The level of screening employed varies. On the main east-west thoroughfares of Constitution and Independence Avenues, barricades are implanted in the roads that can be raised in the event of an emergency. Trucks larger than pickups are interdicted by the Capitol Police and are instructed to use other routes. 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.
All Capitol visitors are screened by a magnetometer, and all items that visitors may bring inside the building are screened by an x-ray device. The U.S. Capitol bans weapons, battery operated devices, recording devices, bags, cans, bottles, creams, perfumes, strollers, food and beverages, and knives in the Gallery.
Finally, 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. Each of the poles is reported to cost $7,500.
The United States Capitol is open for visitation Monday through Saturday through much of the year, including Federal holidays. During the work week, entry into the Capitol can be found through three means. One, procuring passes for a public guided tour from the United States Capitol Guides at a kiosk on the southwest corner of the grounds; second, via reserved tours arranged through one's Senator's or Representative's office; and third, by obtaining gallery passes to view the chambers of the House of Representatives and the Senate (passes are obtained from Representative/Senator office for corresponding chamber, and for international visitors, by simply showing a photo ID to the Capitol Guides). The gallery for the House of Representatives is open for visitation from 9 am to 4 pm Monday through Friday, or while the Representatives are in session. The gallery for the United States Senate is only open when the Senate is in session. Both galleries are closed on Saturday, unless either house is in session.