The Australian Parliament House — known as "New Parliament House" to distinguish it from the original 1927 building down the hill — was designed by the American practice Mitchell/Giurgola & Thorp and opened in 1988 to mark the bicentenary of European settlement. The building is half-buried in Capital Hill so that the grass-covered roof reads as a continuation of the landscape, and to express the architectural conceit that the people walk above the parliament rather than below it.
The free public tours are excellent — they include the marble entrance foyer with its Mabo case carving, the green and red debating chambers (modelled on Westminster but recoloured to soften the colonial reference), the inside of the giant flagpole, and the panoramic view from the roof. Both chambers have public galleries that you can visit whenever Parliament sits, including Question Time, which is the entertaining circus event of Australian politics.