Court of Neptune Fountain

The Library of Congress (LOC) is a research library in Washington, D.C., that serves as the library of the U.S. Congress and the de facto national library of the United States. Founded in 1800, the library is the United States's oldest federal cultural institution. The Library is housed in three elaborate buildings on Capitol Hill. It also maintains a conservation center in Culpeper, Virginia. The library's functions are overseen by the Librarian of Congress, and its buildings are maintained by the Architect of the Capitol. The Library of Congress is one of the two largest libraries in the world, along with the British Library. Its collections contain approximately 173 million items, and it has more than 3,000 employees. Its "collections are universal, not limited by subject, format, or national boundary, and include research materials from all parts of the world and in more than 470 languages."Congress moved to Washington, D.C., in 1800 after holding sessions for eleven years in the temporary national capitals in New York City and Philadelphia. In both cities, members of the U.S. Congress had access to the sizable collections of the New York Society Library and the Library Company of Philadelphia. The small Congressional Library was housed in the United States Capitol for most of the 19th century, until the early 1890s. Most of the original collection was burnt by British forces during the War of 1812. The library began to restore its collection in 1815. The library purchased Thomas Jefferson's entire personal collection of 6,487 books. Over the next few years, its collection slowly grew, but in 1851, another fire broke out in the Capitol chambers. This destroyed a large amount of the collection, including many of Jefferson's books. After the American Civil War, the importance of the Library of Congress increased with its growth, and there was a campaign to purchase replacement copies for volumes that had been burned. The library received the right of transference of all copyrighted works to deposit two copies of books, maps, illustrations, and diagrams printed in the United States. It also began to build its collections. Its development culminated between 1888 and 1894 with the construction of its own separate, large library, now known as the Thomas Jefferson Building, across the street from the Capitol. Two more adjacent library buildings, the John Adams Building, built in the 1930s, and the James Madison Memorial Building, built in the 1970s, hold expanded parts of the collection and provide space for additional library services. The library's primary mission is to research inquiries made by members of Congress, which is carried out through the Congressional Research Service. It also houses and oversees the United States Copyright Office. The library is open to the public for research, although only high-ranking government officials and library employees may check out (i.e., remove from the premises) books and materials.

The Thomas Jefferson Building is the oldest of the four United States Library of Congress buildings. Built between 1890 and 1897, it was originally known as the Library of Congress Building. It is now named for Thomas Jefferson, a Founding Father and the third U.S. president whose own book collection became part of the library in 1815. The building is located on First Street, S.E. between Independence Avenue and East Capitol Street in Washington, D.C. across from the U.S. Capitol. The Beaux-Arts style building is known for its classicizing facade and elaborately decorated interior. The building's main architect was Paul J. Pelz, initially in partnership with John L. Smithmeyer, and succeeded by Edward Pearce Casey during the last few years of construction. The building was designated a National Historic Landmark in 1965.

The congressional office buildings are the office buildings used by the United States Congress to augment the limited space in the United States Capitol. The congressional office buildings are part of the Capitol Complex, and are thus under the authority of the Architect of the Capitol and protected by the United States Capitol Police. The office buildings house the individual offices of each U.S. Representative and Senator as well as committee hearing rooms, staff rooms, multiple cafeterias, and areas for support, committee, and maintenance staff. The congressional office buildings are connected to the Capitol by means of underground pedestrian tunnels, some of which are equipped with small railcars shuttling users to and from the Capitol, which together form the Capitol subway system. Congressional pages are responsible for carrying packages and messages from the two chambers to the buildings. The three Senate office buildings are along Constitution Avenue north of the Capitol: Russell Senate Office Building (RSOB, completed 1908) Dirksen Senate Office Building (DSOB, completed 1958) Hart Senate Office Building (HSOB, completed 1982)The three House office buildings are along Independence Avenue south of the Capitol: Cannon House Office Building (CHOB, completed 1908) Longworth House Office Building (LHOB, completed 1933) Rayburn House Office Building (RHOB, completed 1965)A fourth building, the Ford House Office Building, which used to house the FBI's fingerprint records, sits a few blocks southwest of the others; it houses committee staff and administrative offices. A fifth building, the O'Neill House Office Building (previously known as "House Annex-1") was named after former Speaker of the House Thomas "Tip" O'Neill. The building was demolished in 2002. However, in 2008, Federal Office Building No. 8 (formerly the headquarters of the Food and Drug Administration) was renovated, being renamed the O'Neill House Office Building in 2012. The building was transferred from General Services Administration to the Architect of the Capitol in 2017. It currently houses both House administrative staff as well as offices for the Department of Health and Human Services. The U.S. Capitol Complex also includes a Page Residence Hall and a Capitol Power Plant, both on the House side of the Capitol.

The Mary Pickford Theater, named in honor of silent film star Mary Pickford, is the "motion picture and television reading room" of the United States' Library of Congress in Washington, D.C. It is on the third floor of the Library of Congress Madison building in downtown Washington. The theater screens classic and contemporary movies and television shows, often organized by theme. All screenings are free, though reservations must be made, as the theater accommodates only 64 people. In 2020, showings were postponed due to the COVID-19 pandemic.

The United States Capitol Visitor Center (CVC) is a large underground addition to the United States Capitol complex which serves as a gathering point for up to 4,000 tourists and an expansion space for the U.S. Congress. It is located below the East Front of the Capitol and its plaza, between the Capitol building and 1st Street East. The complex contains 580,000 square feet (54,000 m2) of space below ground on three floors. The overall project's budget was $621 million.The CVC has space for use by the Congress, including multiple new meeting and conference rooms. On the House side, there is a large room which will most likely be used by a committee. The new Congressional Auditorium, a 450-seat theater, is available for use by members of Congress or for either House of Congress should their respective chamber be unavailable.The CVC officially opened on December 2, 2008. This date was selected to coincide with the 145th anniversary of placing Thomas Crawford's Statue of Freedom atop the Capitol building in 1863, signifying the completion of construction of its dome.

The Moldenhauer Archives at the Library of Congress is a collection of original music, unique documents and manuscripts within the Library of Congress, the national library of the United States. The Moldenhauer archives contains many thousands of unique original documents of historical significance. Part of the collection was bequeathed to The Moldenhauer Archives at Harvard University, located in the Houghton Library at Harvard University.

The Old Brick Capitol in Washington, D.C., served as the temporary Capitol of the United States from 1815 to 1819. The building was a private school, a boarding house, and, during the American Civil War, a prison known as the Old Capitol Prison. It was demolished in 1929, and its site is now occupied by the U.S. Supreme Court building.

The Cannon House Office Building, often called the "Old House Office Building," completed in 1908, is the oldest congressional office building as well as a significant example of the Beaux-Arts style of architecture. It occupies a site south of the United States Capitol bounded by Independence Avenue, First Street, New Jersey Avenue, and C Street S.E. In 1962 the building was named for former Speaker of the United States House of Representatives Joseph Gurney Cannon.

The Law Library of Congress is the law library of the United States Congress. The Law Library of Congress holds the single most comprehensive and authoritative collection of domestic, foreign, and international legal materials in the world. Established in 1832, its collections are currently housed in the James Madison Memorial Building of the Library of Congress. Law staff rely on and utilize 2.9 million volumes of primary legal sources, 102.18 million microforms, 99,000 reels of microfilm, 3.18 million pieces of microfiche, and 15,600 tangible electronic resources (CD-ROMs and other disks), making it is the largest law library in the world.

The Supreme Court Building houses the Supreme Court of the United States. Also referred to as "The Marble Palace", the building serves as the official workplace of the chief justice of the United States and the eight associate justices of the Supreme Court. It is located at 1 First Street in Northeast Washington, D.C., in the block immediately east of the United States Capitol and north of the Library of Congress. The building is managed by the Architect of the Capitol. On May 4, 1987, the Supreme Court Building was designated a National Historic Landmark.Built in the neoclassical style, the proposal for a separate building for the Supreme Court was suggested in 1912 by President William Howard Taft, who became Chief Justice in 1921. In 1929, Taft successfully argued for the creation of the new building, but did not live to see it built. Physical construction began in 1932 and was officially completed in 1935 under the guidance of Chief Justice Charles Evans Hughes, Taft's successor. The building was designed by architect Cass Gilbert, a friend of Taft.

Sojourner Truth is a public artwork by Canadian sculptor Artis Lane, located in Emancipation Hall at the United States Capitol Visitor Center in Washington, D.C. It was the first statue honoring an African-American woman in the U.S. Capitol building.

The James Madison Memorial Building is one of three United States Capitol Complex buildings that house the Library of Congress. The building was constructed from 1971 to 1976, and serves as the official memorial to United States Founding Father and president James Madison. It is located between First and Second Streets SE on Independence Avenue, in Washington, D.C.. In addition to various book and multimedia collections, it houses the United States Copyright Office, which is under the jurisdiction of the Librarian of Congress.