The first congressional office buildings were constructed immediately after the turn of the century to relieve overcrowding in the U.S. Capitol Building. Previously, members who wanted office space had to rent quarters or borrow space in committee rooms. In March 1901 plans were drawn for fireproof office buildings adjacent to the Capitol Grounds. In March 1903, the acquisition of sites and construction of the buildings were authorized. In April 1904, the prominent New York architectural firm of Carrère and Hastings was retained. Thomas Hastings took charge of the House Office Building project, while John Carrère oversaw the construction of an almost identical office building (now named the Russell Senate Office Building) for the Senate. Their Beaux Arts designs were restrained complements to the Capitol.

Column bases in place during the construction of the Cannon Building's colonnade in November 1906.

Architecturally, their elevations are divided into a rusticated base and a 300 foot colonnade with an entablature and balustrade. The colonnade with 34 Doric columns that face the Capitol are echoed by pilasters on the sides of the buildings. Both buildings are faced with marble and limestone; the Russell Building's base and terrace are gray granite. Modern for their time, they included such facilities as forced-air ventilation systems, steam heat, individual lavatories with hot and cold running water and ice water, telephones, and electricity. Both are connected to the Capitol by underground passages. Originally there were 397 offices and 14 committee rooms in the Cannon Building; the 1932 remodeling resulted in 85 two- or three-room suites, 10 single rooms and 23 committee rooms.

Each member of the House of Representatives was given a single, relatively modest room to use as an office. It was only 15 feet wide, 23 feet long, and furnished with a roll top desk, chairs, a wardrobe, and filing cabinets. Modern in every respect, the offices were also outfitted with telephones, lavatories (supplying hot, cold, and ice water), steam heat, and forced-air ventilation. Members of the House also had use of the building's bathing rooms, barber shop, telegraph office, restaurant and cafe.

Of special architectural interest is the rotunda. Eighteen Corinthian columns support an entablature and a coffered dome, whose glazed oculus floods the rotunda with natural light. Twin marble staircases lead from the rotunda to an imposing Caucus Room, which features Corinthian pilasters, a full entablature, and a richly detailed ceiling. The Cannon Building was occupied during the 60th Congress on December 12, 1908. By 1913, however, the House had outgrown the available office space, and 51 rooms were added to the original structure by raising the roof and constructing a fifth floor. In 1962, the building was named for former Speaker Joseph Gurney Cannon.

Read more about the history of the Cannon House Office Building.