Architecturally the building is considered outstanding. Much trouble was taken in selecting building materials from within South Australia to reflect the colony's pride in its own resources. The house is built of marble from Kapunda (just north of the Barossa Valley) for its beauty and durability and sits on a base of granite from West Island near Victor Harbor. Even the plainer, northern face is relieved by an elegant balcony on the first floor.

The original design by Wright and Tayler as shown here included an enormous central dome and other external embellishments, but like the carved faces in the windows, these luxuries had to be forgone on the 1930s addition which completed the building as during that 50 year span the State had experienced two depressions and a world war and the State simply did not have the money to pay for such embellishments. To compensate the columns in the portico were increased from six to ten.