The Building houses two Assembly rooms, and the offices of the President and Prime Minister. 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 the United Commonwealths. A number of features in the structure commemorating the formation of the United Commonwealths.The structure consists of four floors,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. On the north facade, the entrance is framed by eight Corinthian columns reached by 42 granite steps. A similar entrance 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. The building has a rectangular footprint and is constructed of brick and concrete and faced on the exterior with limestone quarried from Wilkeson, Washington. The Building is also home to a large brass bust of George Washington.