The building's vast open space is more than and occupies two full city blocks. It is between Van Ness Avenue and Polk Street, and between Grove and McAllister Streets. Its dome, which owes much to Mansart's Baroque domes of the Val-de-Grâce (church) and Les Invalides in Paris, rises above the Civic Center Historic District. It is higher than the United States Capitol, and has a diameter of , resting upon 4 x 50 ton (44.5 metric ton) and 4 x 20 ton (17.8 metric ton) girders, each deep and long.