A section of the Extinction Rebellion, the protest group glued themselves to the bitumen surface, calling for immediate action on climate change ahead of the UN Glasgow summit later this month.
It's understood the group also glued themselves to prams at the corner of King William and Grote Street.
Adelaide locals were furious with the stop in traffic, saying the rally was meaningless.
"Wasting Police precious time that's what it is," one woman said.
"It's not going to achieve anything" said a local on-looker.
The COP26 summit is set to be the most important climate meeting in the past five years, with Prime Minister Scott Morrison to announce Australia's commitment to the net zero emissions by 2050 plan.
Police closed the road while they attempted to remove the protesters who had glued themselves to the road making arrests around 10.30am.
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