A minute's silence has been marked across Australia in tribute to the late Queen Elizabeth II.
Prime Minister Anthony Albanese and Governor-General David Hurley signed a condolence book ahead of the pause for reflection at the start of a national memorial service at Parliament House.
Their procession into the Great Hall was led by Indigenous performers Wiradjuri Echoes.
Political leaders past and present, judges, military chiefs and other dignitaries are among 700 guests at the service.
Mr Hurley, Mr Albanese and Opposition Leader Peter Dutton will speak during the televised service, which will also feature a Bible reading, prayers, music and a floral tribute.
Inside the Great Hall, among the sea of black suits, dresses, hats and veils, could be seen the bright orange of SES volunteers, red of Scout uniforms and blues and greens of school uniforms.
The Queen died on September 8 aged 96, having reigned as Australia's head of state for 70 years.
Twenty years ago she declared during a visit to Australia her "admiration, affection and regard for the people of Australia will remain, as it has been ...constant, sure and true".
Up to six Royal Australian Air Force F-35A Lightning II jets from No.77 Squadron will fly past parliament at midday.
The Queen visited the country 16 times during her reign and was the patron of more than 20 Australian charities and associations.
She consulted with 16 prime ministers and 16 governors-general served in her name.
Former prime ministers Paul Keating, John Howard and Scott Morrison are attending the memorial service.
All eight state and territory leaders are present, as arestate governors, justices of the High Court and religious leaders.
Cabinet minister Tanya Plibersek said it was an important day to mark 70 years of service.
"This is a once in a lifetime opportunity to mark the passing of a very special woman," she said.
Indigenous Australians Minister Linda Burney, who is taking part in the service, said she believed it would be received "very respectfully" by Indigenous people.
"There is a huge respect for sorry business - it is part of Aboriginal culture and the reverence to the Queen in my view falls into that category," she told ABC radio.
However, she said there was a "complex relationship" between Indigenous people and the monarchy.
"You cannot divorce the issues of colonisation from the role of Britain going back through the ages."
Opposition frontbencher Karen Andrews, who is also attending the service, said it would be a "fitting tribute".
A 1954 painting of the Queen by eight-time Archibald Prize winner Sir William Dargie is the centrepiece of the service.
The painting is surrounded by Australia's floral emblem, the golden wattle, and some of her favourite flowers, sweet peas and dahlias.
Former Australian Idol contestant Anthony Callea is performing at the service.
Both houses of parliament will sit on Friday to speak on a condolence motion for the Queen and pay tribute to King Charles III.
