A community group is seeking to buy Sydney's controversial Sirius building in a bid to save the harbourside social housing block from the wrecking ball.
Save our Sirius foundation chairman Shaun Carter has vowed to continue the fight to save the brutalist Rocks icon after the NSW government put the building on the market in December.
"We are happy to play the government's game. Our intentions are absolutely pure: we want to save Sirius because of its important social and cultural heritage," Mr Carter told AAP on Friday.
With a price tag of about $100 million, the group want to buy the building, preserve it as social housing and get it listed on the State Heritage Register.
The state government has twice rejected a bid to put the building on the register, despite experts saying it should be.
In another attempt to save the harbourside block, it was slapped with an interim green ban in 2016 by the NSW Construction, Forestry, Mining and Energy Union, which means no unionised workforce will be involved in its demolition.
If SOS isn't successful in its registered interest to purchase the building, the group won't let it be demolished, Mr Carter says.
"We will physically stand in their way," he said.
"Sydney has a long history to fight for what it believes in."
The building's last resident, 91-year-old legally blind Myra Demetriou, will be relocated in February.
"Myra is going because she's been forced out," Mr Carter said.
"The government has taken away the ability to have a home and be safe and secure."
A farewell morning tea will be held on site for Mrs Demetriou on Saturday morning with Sydney City Lord Mayor Clover Moore and deputy opposition leader Tanya Plibersek in attendance.