Papua New Guinea has raised its national flag to mark 40 years of independence from Australia.
Tens of thousands of people wearing the national colours of red, black, white and gold turned out for the ceremony outside Parliament House in Port Moresby after dawn with fighter jets flying overhead.
Prime Minister Peter O'Neill says the nation is also celebrating thousands of years of rich tribal history, traditions and culture.
The United Nations Resident Co-ordinator, Roy Trivedy, says 40 years is a fantastic achievement.
He says not only has the nation reached an important milestone of 40 years of continuous democracy, it has continued to encourage its many diverse communities to have a genuine voice in PNG's development and its achievements.
Mr Trivedy says maintaining this unity and diversity will be vital for the country's future.
Becoming a nation
A former Papua New Guinea prime minister says people of the country are increasingly identifying themselves as being part of a nation over being part of a tribe.
Sir Rabbie Namaliu, who was prime minister from 1988- 1992, says the country has its share of big challenges but that, considering its sheer diversity, PNG has done remarkably to hold it together as a democratic nation.
He says the integration of the country's many remote parts through advances in areas like telecommunications has helped foster the sense among Papua New Guineans of belonging to a much wider community.
"I mean the country ten years ago did not have a mobile technology industry. Well, today we have one of the most flourishing in the whole of the Pacific, and I think that alone has helped to transform the country in ways that no one would have imagined ten years ago."
Sir Rabbie Namaliu says the key to keeping the country together and moving forward on its challenges is education.
He says if PNG can continue to drive education, this will serve as an instrument to unite the country and take its economic and social growth to the next level.
"After forty years, I think we have more Papua New Guineans thinking of being one country or as being Papua New Guineans, rather than belonging to their own individual tribes and that's good, but it's not finished. It's not finished business. We've got to continue to emphasise that the nation is still young and it's got a long way to go."