Cannon Building

Brief Information

The Cannon Building emerged as a practical solution to the overcrowding in the Capitol: members of Congress had previously had to rent offices or occupy committee rooms. Built in 1908 south of the Capitol, it became the oldest office building of the U.S. Congress, while being conceived not as a rival to the main building, but as a restrained addition to it.

This service role clearly explains its design. On the outside, the building maintains a solemn Beaux-Arts style, while inside it was originally a modern working mechanism with ventilation, heating, telephones, electricity, and individual restrooms. When the number of offices quickly became insufficient, a fifth floor with 51 rooms was added on top, but it was hidden so that it is visible only from the enclosed courtyard, not from the facade.

What to Notice First

It is worth comparing the strict exterior order with the building’s hidden service logic. The facades are divided into a rusticated base, colonnade, entablature, and balustrade: the lower part looks heavier, while the upper part gathers the building into a ceremonial rhythm. Thirty-four Doric columns face the Capitol and echo the pilasters along the sides, so the office building visually adapts itself to the neighboring center of power. Marble and limestone reinforce this official character.

Inside, the main focus is the rotunda. Eighteen Corinthian columns support the entablature and coffered dome, while the glazed oculus provides natural light. Double marble staircases connect the rotunda with the Caucus Room, where Corinthian pilasters, a full entablature, and a detailed ceiling appear again. Underground passages to the Capitol and other buildings reveal the other side of the design: here, ceremonial architecture is directly connected with the daily work of Congress.