Sydney has a wide variety of cultural sites and institutions. Sydney's iconic Opera House has five theatres capable of hosting a range of performance styles; it is the home of Opera Australia, the third busiest opera company in the world and the Sydney Symphony Orchestra. Other venues include the Sydney Town Hall, City Recital Hall, the State Theatre and the Wharf Theatre. The Sydney Dance Company under the leadership of Graeme Murphy during the late 20th century has also gained acclaim. The Sydney Theatre Company has a regular roster of local plays, such as noted playwright David Williamson, classics and international playwrights. Other important theatre companies in Sydney include Company B and Griffin Theatre Company. Sydney hosts many different festivals including the Sydney Festival, a celebration involving both indoor and free outdoor performances throughout January. Sydney has several museums. The biggest are the Australian Museum (natural history and anthropology), the Powerhouse Museum (science, technology and design), the Art Gallery of New South Wales, the Museum of Contemporary Art and the Australian National Maritime Museum.