The Social Research Centre alongside the Australian National University surveyed 2074 people aged between 18 and 93 years old to identify the top 10 most significant events for the nation, ranking the legalisation of same-sex marriage at number 1.

The Life in Australia Historic Events Survey, conducted in late 2017 just after the same-sex marriage announcement, placed the September 11 terrorist attacks in 2001 second, with 27 per cent of people recognising the impact on Australians.

Since the 2001 attacks, Australia's defence spending and ASIO's budget increased dramatically, and security and anti-terrorism legislation became much more severe.

SRC chief executive Darren Pennay said it was not surprising the same-sex marriage issue was a popular choice due to the proximity of the survey to the vote.

"It's quite a unique opportunity to see the significance associated to that event," he said.

Mr Pennay said it would be interesting to see where Australians would rank the legislation in 10 years time.

"No doubt as same-sex marriage becomes part of everyday life it might lose some of its impact," he said.

Kevin Rudd's apology to Indigenous Australians was third, with the Port Arthur Massacre in 1996 rated fourth.

The Sydney Olympics ranked fifth before the dismissal of the Whitlam Government at sixth and the Vietnam War seventh.

For Mr Pennay, the most historic event to shape his lifetime was the Apollo 11 moon landing.

"I had the day off school and watched it on television," he said.

"I remember I looked up in the sky that night and imagined there were people walking around up there - it was quite mind-blowing for an eight-year-old."

The Apollo 11 moon landing and the arrival of the internet came eighth and ninth, with Australia's II's America's Cup victory, the Global Financial Crisis and the election of Julia Gillard as the first female prime minister, coming in equal tenth, all getting 8 per cent of the vote.

Australians felt proudest of same-sex marriage (13 per cent) and the Sydney Olympics (10 per cent) while Australia's treatment of asylum seekers left the most people feeling disappointed.

Mr Pennay said human rights, terrorism, Australian politics and war were the most recurrent themes across all age groups.

"We are undoubtedly living through turbulent times both domestically and internationally and the results show a keen interest in matters both here and abroad," he said.

"As we approach Australia Day 2018, it is also striking that Indigenous issues such as the apology, the Mabo decision and the 1967 Aboriginal referendum continue to resonate in our collective memory (mentioned by 24 per cent) as do immigration-related events such as the refugee crisis and offshore detention centres, mentioned by 14 per cent of participants," he said.

There were differences between what men and women marked as the most important: men ranked September 11 as the most significant (27 per cent) and women nominated same-sex marriage (35 per cent).

Baby Boomers marked the Vietnam War as the most significant, while for the Silent Generation (born 1945 or before) it was World War II.

For Generation X it was September 11, and millennials and Generation Z it was same-sex marriage and terrorism-related events.

1. Same-sex marriage, 2017 - named by 30% of survey participants

2. 9/11, 2001 - 27%

3. Apology to Indigenous Australians, 2008 - 13%

4. Port Arthur Massacre, 1996 - 13%

5. 2000 Sydney Olympics, 2000 - 12%

6. Sacking of the Whitlam Government, 1975 - 12%

7. Australia's involvement in the Vietnam war, 1962-1973 - 11%

8. Moon landing, July 1969 - 9%

9. The Internet / Worldwide Web, 1989 - 9%.

10. America's Cup win, 1983 - 8%, Global Financial Crisis, 2008 - 8%, first female prime minister, 2010-2013 - 8%