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 on the exterior and from the floor. 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.