It is located just south of Interstate 84 and west of the Legislative Office Building, on the east side of Broad Street.

The building functionally has two sections: a three-story "head house", in which offices and other facilities are located, and a large drill hall with a gabled roof.

The main entrance is set in the center of a broad projecting section of the headhouse, in a round-arch opening.

The interior of the drill hall is 1.14 acres (0.46 ha) in size, with a ramp from Broad Street providing ready access for the movement of heavy equipment.

Its design was by Benjamin Wistar Morris III, who had worked as draftsman at Carrere & Hastings before opening his own office in New York City in 1900.