Thousands came together on Wednesday to sit on the lawn and stand on the steps outside the State Library, among the statues of Joan of Arc and St George, and hear what the people had to say.

As the ABC feed blared out across the crowd just after 10am, the tension was unbearable. It didn't help that the sound was breaking up. Some held hands, others couldn't look.

And then the nation's chief statistician said the words the crowd was longing to hear, kicking off a joyous, city-wide party.

There was glitter, there was colour, there was music. Kissing and proposals too, with lots of tears, as the celebration erupted.

"I came today with some trepidation," said Amelia Basset, who was there with her partner, Jo Smale. "I can't believe it's a 'yes'."

This wasn't an outpouring fuelled solely by joy. There was also relief, sadness, anger and frustration. But the voters' verdict was emphatic and, after months of campaigning, the crowd was going to enjoy the moment.

George Papagiannopoulos and Luke Meehan came dressed in floor-length white dresses bought at an op shop. They said they had been overwhelmed with support from friends and family.

"We're feeling the love," said Mr Meehan.

Nick Eymaud and Simon Fitzpatrick wore beaming smiles but, like many, felt exhausted after the effort it had taken to get to this point.

When the result was announced, Mr Eymaud said his body "just crumpled".

"I was really scared this morning, not for myself but terrified for the young kids who don't have the support," he said.

"Now that it's a 'yes' I just feel like this huge weight lifted off my shoulders."

After the formalities were done, the sparkling wine flowed freely as disco hits and Queen tracks boomed out to dancing revellers.

Crowds of people decked in rainbow colours descended on bars across Melbourne to enjoy a hard-earned drink. At State Parliament, the rainbow flag fluttered as it was hoisted high above the city.

Outside Loop Bar, in Meyers Place, Peter Clarke got down on one knee and proposed to his partner Steve Lowe. The couple have been together 10 years and hope to get married as soon as the legislation is passed.

There was no ring, but Peter wants to do all the things other couples have been permitted to do. First off, it's the engagement party.

"It means that we're recognised as a union in the eyes of everybody in Australia," Mr Clarke said.

Reservoir's Zoe McDonald and Katie Larsen are already preparing for their wedding in October next year.

The pair were planning to get hitched before the survey was announced, but said being able to get legally married will feel different.

"You tell yourself that it won't, that it will be the same," Ms McDonald said. "But I think it feels so much more solid or grounded."

In the Alexandra Gardens, engaged couple Adam Seymour and Sam Cremean were ecstatic and relieved as they sipped champagne with friends.

"I'm so happy and proud of everyone in Australia coming together and making this come true," said Mr Seymour.

Victoria's regional centres also held their own celebrations. In Bendigo, Ashlyn McDonald said it made her proud to live in her city. Ballarat's Kirsten Holden had a similar reaction.

"It's a big thing for us to know we have the support of the majority of the community," she said.

Back in Melbourne, the revelry was poised to continue long into the night at Trades Hall in Carlton, where music played and the booze flowed freely.

Holding an anti-Tony Abbott sign, Viana Van Eyk said she wanted her "white picket fence" and the "right to have a messy divorce".

In the meantime, she said, "we're going to party hard".

With Carolyn Webb and Robyn Grace

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