The construction of the Capitol began in 1793, and for over a century it was the only building created for the use of the nation's legislature. In fact, the Capitol initially housed not only the Congress but also the Library of Congress, the Supreme Court, the district courts, and other offices. In the following decades the nation grew dramatically, and as a result, so did the Congress. The Capitol and its grounds were enlarged accordingly, and by 1892 the building had reached essentially its present size and appearance (with the exception of the east front extension [1958-1962] and courtyard infill areas [1991-1993]).
Despite the enlargement of the Capitol, the crowding inside soon became intolerable: in addition to the House and Senate, the building still housed the Library of Congress and the Supreme Court. In 1897 the Library departed the Capitol for its own separate building, which is today known as the Thomas Jefferson Building; this event marks the beginning of the development of the present Capitol complex of buildings. It was followed in short order by the construction of the first separate buildings for the House and Senate. Like the Library of Congress building, these were first known by "generic" names: the House Office Building (now named the Cannon House Office Building) was opened in 1908, and the Senate Office Building (now named the Russell Senate Office Building) was opened the next year. They were provided with steam for heating (and, originally, electricity) by the new Capitol Power Plant, which became operational in 1910 and subsequently underwent several expansions.
The 1930s was a decade of major construction within the growing Capitol complex. In 1933 alone the U.S. Botanic Garden Conservatory, Director's residence, and Bartholdi Park were completed; the Senate Office Building's First Street wing, which had been omitted during construction for funding reasons, was added; and the Additional House Office Building (later named the Longworth House Office Building) was occupied. The Supreme Court at last found a permanent home when its own building was completed in 1935. The last building constructed within the complex in this decade was the Library of Congress Annex, now named the John Adams Building, which opened in 1939.
Within twenty years attention returned to the need for more congressional office space; this led to the construction of a second building for the Senate (now named the Dirksen Senate Office Building), which was completed in 1958. The House's third building, the Rayburn House Office Building, opened in 1965. In the 1970s two more buildings became available for the House: the former Congressional Hotel (named the O'Neill Building; demolished in 2002) and a larger building originally constructed for the FBI (now the Ford Building). A third building for the Library of Congress, the James Madison Memorial Building, opened in 1980; the Senate's third building, the Hart Senate Office Building, was occupied in 1982. The most recent large structure within the Capitol complex is the Thurgood Marshall Federal Judiciary Building, which was opened in 1992.
The major supporting facility added in the last quarter-century is the Botanic Garden's Production Facility, which was constructed in D.C. Village, a section of Anacostia, in 1989.
As the twenty-first century opens, the Capitol complex is still growing and changing. The renovation of the Botanic Garden Conservatory is nearing completion, and work will soon begin on the adjacent National Garden, a new educational and display facility. The Capitol dome is being rehabilitated in a project that will abate lead-based paint, repair cracks in the cast-iron skin, apply new paint inside and outside, and effect other related work. Fire-protection and life-safety upgrades are being performed throughout the complex, and planning and development work are ongoing for the new Capitol Visitor Center, which will be constructed under the east front plaza.
