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 287 feet (87 m) high, making it the tallest self-supporting masonry dome in North America,[29] 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.[1] 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.[30] The building has a rectangular footprint and is constructed of brick and concrete and faced on the exterior with sandstone quarried from Wilkeson, Washington. The structure consists of four floors with the dome at the center that reaches a height of 287 ft (87 m) on the exterior and 175 ft (53 m) from the floor.[1] The first floor is within the raised base and houses offices. The second and third floors are surrounded by Doric columns and capped with a cornice that encircles the building. The fourth floor is covered with a gabled roof that is situated behind the cornice on the third floor. On the north facade, the entrance is in a portico framed by eight Corinthian columns reached by 42 granite steps. A similar portico is on the south facade but it covers a vehicle ramp to the lower level instead of steps. The dome is surrounded by four small sandstone domes and capped by a lantern and lightning rod. The floors and many interior walls are covered by Alaskan marble and marble from Belgium, France, Germany, Italy are used in other parts of the interior.[30]