Old Government Buildings was designed in the classically-derived Italian Renaissance revival style. Like many colonial buildings of the era, it was built to resemble a stone palace. This was to convey strength and stability in a young country undergoing rapid growth and change.

It features include two staircases, eight vaults, 143 rooms, 126 fireplaces, 22 chimneys, two hydraulic lifts, 64 toilets, eight verandas and seven porticos. Government ministers used the building during Parliament's recess until 1921. The Executive Council met in the building until 1948.