A rainbow-coloured path has been unveiled in Adelaide's CBD to recognise and celebrate the city's LGBTI history.

The Rainbow Walk in Light Square includes a timeline to highlight milestones for sexual minorities in South Australia.

Former Adelaide City Councillor and Greens Senator, Robert Simms, said the installation would send a positive message about the gay and lesbian community,

"We have a very proud story to tell here in South Australia - we were the first state in the country to decriminalise homosexuality," he told 891 ABC Adelaide.

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"The reason why I put this project forward when I was on council was so that we could recognise that tradition and really celebrate that proud history."

Mr Simms said despite the state's progress, there was still room on the rainbow path for more achievements.

"It's a reminder of how far we've come on the journey for law reform for LGBTI Australians, but it's also a reminder too this rainbow doesn't end and we've still got work to do."

Adelaide Lord Mayor Martin Haese said the city's West End was the perfect home for the Rainbow Walk.

"It looks very fitting, it looks like it absolutely belongs in Light Square... I think it's really come up a treat."

The path is in the north-western section of Light Square near the Adelaide College of the Arts.

The launch, which featured performer Dannii Minogue, also marks the start of the city's annual Feast Festival.