The Legislative Building houses the chambers of the Washington State Legislature and offices of several elected officials. This building is the dominant feature of the capitol grounds, with its dome high, making it the tallest self-supporting masonry dome in the United States, and fifth tallest in the world, surpassed only by St. Peter's Basilica in Rome, St. Paul's Cathedral in London, Global Vipassana Pagoda in Mumbai, and Santa Maria Del Fiore in Florence. A number of features in the structure commemorating Washington's addition to the Union as the 42nd state—42 steps lead to the building's North entrance and one of the four 42-star flags owned by the state is displayed in the State Reception Room. Flags with this number of stars were never official because of the admission of Idaho shortly after Washington.