Parliament House, also referred to as Capital Hill or simply Parliament, is the meeting place of the Parliament of Australia, and the seat of the legislative branch of the Australian Government. Located in Canberra, the Parliament building is situated on the southern apex of the Parliamentary Triangle atop Capital Hill, at the meeting point of Commonwealth, Adelaide, Canberra and Kings Avenue enclosed by the State Circle. Parliament House was designed by Mitchell/Giurgola & Thorp Architects and built by a Concrete Constructions and John Holland joint venture. It was opened on 1988 by Elizabeth II, Queen of Australia. It cost more than A$1.1 billion (equivalent to about $ billion in ) to build. Federal Parliament meetings were held in Melbourne until 1927. Between 1927 and 1988, the Parliament of Australia met in the Provisional Parliament House, which is now known as "Old Parliament House". The construction of Australia's permanent Parliament House was delayed while its location was debated. Construction of the new building began in 1981. The principal design of the structure is based on the shape of two boomerangs and is topped by an flagpole.The flag that is hoisted on this pole is one of the largest hoisted in the country.Their measurements had by . The Parliament House contains 4,700 rooms, and many areas are open to the public. The main foyer contains a marble staircase and leads to the Great Hall, which has a large tapestry on display. The House of Representatives chamber is decorated green, while the Senate chamber has a red colour scheme. Between the two chambers is the Members' Hall, which has a water feature and is not open to the public. The Ministerial Wing houses the Prime Minister's Office and other ministerial offices. Before the establishment of Canberra In 1901, when the six British colonies in Australia federated to form the Commonwealth of Australia, Melbourne and Sydney were the two largest cities in the country, but the long history of rivalry between them meant that neither could become the national capital. Section 125 of the Constitution of Australia therefore provided that: The seat of Government of the Commonwealth shall be determined by the Parliament and shall be within a territory which shall have been granted to or acquired by the Commonwealth, and shall be vested in and belong to the Commonwealth, and shall be in the State of New South Wales, and be distant not