The site covers . The building was designed to sit above Old Parliament House when seen from a distance. The building is four metres (13 feet) higher than the original height of the hill. About one million cubic metres (35,000,000 cubic feet) of rock had to be excavated from the site. It was used to fill low-lying areas in the city. Most of the granite used was sourced from Australia. Twice the amount needed was quarried as a very high standard of granite was required particularly for the curved walls.