The Sydney Opera House, is one of the most significant architectures created in the twentieth century and such as to represent almost an icon not only for the city of Sydney, where it stands, but for Australia itself. The project is designed by the Danish architect Jorn Utzon, who is assisted by structural calculations by the London-based engineering company Arup, located in Sydney, with an amusement park to the south and a large car park accessible from Macquarie Street. connected and close to the huge Sydney Harbor Bridge, the building and its surroundings are often a destination for tourists who - for the most part without any interest in the opera - crowd the building simply to visit the structure. , the shells with spherical section can remember the flotilla of sailboats that goes on a cruise in the Australian seas The acoustics of the whole structure, particularly that of the teat of the work, has not always had appreciation and indeed has received criticism to be judged unsatisfactory with respect to the function for which it was created. There have been constant requests for a renovation of the spaces, a restyling that involves moving the opera house to the larger and more acoustically appropriate concert hall, with the consequent relocation of the Sydney Symphony Orchestra into a new hall. On September 28, 1973, the pre-inauguration of the Opera House took place with Voina i mir (War and Peace) by Sergei Prokofiev. The opera house (Opera Theater with 1,530 seats) was inaugurated by Queen Elizabeth II on October 20, 1973. The opening was broadcast on television, with fireworks and the performance of Beethoven's Ninth Symphony. In the 2,700-seat concert hall there is the great pipe organ, an organ with 10,500 pipes, installed in 1979. In 2007 it became part of the world heritage under UNESCO.