The Old Senate Chamber is considered one of the oldest parts of the U.S. Capitol Building.
The Old Senate Chamber  as it exists today is the third Chamber created for the use of the Senate in the U.S. Capitol . The original Chamber, designed by Dr. William Thornton , was located on the ground floor of the north wing. However, the wing deteriorated so rapidly that plaster walls and ceilings were crumbling and wooden floors were rotting after only 6 years of use.
Consequently, Capitol architect Benjamin Henry Latrobe  decided to gut and completely rebuild the interior of the wing. Using vaulted construction, as he had in building the south wing, Latrobe raised the Chamber to the second or principal floor to make it level with the Old Hall of the House (now called National Statuary Hall). A ground-floor Chamber just below the Senate was created for the Supreme Court. Construction began in 1808 and the Senate moved into the space 2 years later. However, occupancy of the new quarters was short lived: the Senate Chamber was destroyed by fire, along with most of the rest of the building, during the War of 1812. Latrobe returned to Washington to oversee the Capitol rebuilding project and, at the request of the Senate, enlarged the Chamber to its present dimensions. Architect Charles Bulfinch  assumed control of the reconstruction effort following Latrobe's resignation, and he completed the Chamber by December 1819.
The Senate met in this Chamber continuously for the next 40 years. During this period, the Senate was embroiled in the great national debates of the 19th century, with slavery the dominant issue. The Missouri Compromise of 1820 was hammered out here. The Hayne-Webster debates of 1830, concerning the right of states to nullify federal laws, were staged here, as were the Webster-Clay-Calhoun debates of 1850. Washington's elite gathered to watch the impassioned oratory and the great compromises that took place in this Chamber.
The United States grew rapidly during the 19th century, and the growing membership in Congress prompted an enlargement of the building during the 1850s. In 1859 the Senate relocated to its more spacious present Chamber in the new Senate wing . The vacated meeting place was quickly claimed by the Supreme Court, which moved to the second-floor Chamber in 1860. The Court continued to meet in the room for 75 years. The Court's tenure in the Capitol had always been considered temporary, and in 1935 the long-awaited Supreme Court building  finally opened. Following the Court's departure, the space was used as a meeting room until its restoration in 1976.
The Old Senate Chamber was returned to its mid-19th-century appearance in anticipation of America's bicentennial. Few original furnishings were available for display in the restored Chamber, and thus many of the objects had to be reproduced based on historical evidence and informed conjecture. An 1842 engraving of the Chamber by Thomas Doney, with its careful attention to details of the room's architecture and furnishings, was an important source of information for the restoration. Structural modifications made to the Chamber included the installation of a new raised floor over existing masonry. Existing ceiling beams were covered with fire-resistant material, and coffer ornaments were recast in plaster. The Ladies' Gallery, which had been removed in the 19th century, was entirely reconstructed. On the north and south walls, marble faces and mantels were faithfully copied from the east wall mantels, which are original to the room. The carpet pattern was derived from contemporary illustrations of the Chamber, as was the design for the oil- burning chandelier, which was electrified for practical reasons but designed to simulate the glow of oil illumination. The Webster desk was selected as the prototype for the reproductions of the Senators' desks because it survives in its original condition. Similarly, the existing Vice President's desk was used as a model for the creation of a new clerk's desk. The gilt eagle and shield are original to the Chamber, while the reproduction of the canopy was based on a variety of illustrations.
Today the restored Chamber is used primarily as a museum, recreating the scene of many significant moments in the evolution of the United States Senate and the legislative history of the nation.