Sydney's controversial Sirius building will soon sit empty with its last resident, a blind 90-year-old woman, forced to pack her bags.

Myra Demetriou is considered the face of the campaign to save the historic brutalist housing block in The Rocks.

The social housing apartments were unanimously recommended for protection by the Heritage Council, but the Government ignored that advice, putting the building up for sale to developers last year.

"It's so ridiculous, I don't know who they think they are," Ms Demetriou, who has lived in the Millers Point area for 60 years, said.

"They say they need the money — they need the money like a hole in the head.

"We'd have more rights in jail."

Tanya Plibersek (R) said Millers Point will not be the same without Myra Demetriou (L). ( ABC News: Emily Laurence )

Those who have fought for the survival of Sirius see it as a symbol of the community and want to preserve social housing close to the city.

Member for Sydney and Deputy Leader of the Opposition Tanya Plibersek spoke at Ms Demetriou's farewell on Saturday morning, and called her "the glue" that held the Millers Point community together.

The view inside 90-year-old resident Myra Demetriou's apartment. ( ABC News: Paige Cockburn )

"Myra is the sort of person who makes a suburb into a community," she said.

"Myra we love you."

The decision to sell was "heartless", Ms Plibersek said, and hollowed out the city by making it more homogenous.

Sydney Lord Mayor Clover Moore said Sirius was a symbol of the state's "shocking inaction" to provide affordable social housing.

"Here Sirius stands purpose built, and there has never been a greater need," she said.

"From every point of view, social, environmental, heritage and community what is happening here is wrong.

"In contrast, Myra, you have been a champion."

'We will play the Government's game'

Campaigners of the non-for-profit Save Our Sirius (SOS) organisation had big news at Ms Demetriou's farewell on Saturday — they announced they will lodge a bid to buy the building.

"We are going to play the Government's game," SOS chairperson Shaun Carter said.

While they did not reveal how they would raise the $100 million the Government is asking, Mr Carter hinted it was not only individuals that care, but also corporations.

"Corporations who have some social capital funds may be able to invest in this," he said.

"We think it's a safe bet if you invest with our organisation you won't lose your money but what you will be doing is putting diversity and equality in the heart of the city."

The Sirius building at Millers Point is a well-known example of brutalist architecture. ( Supplied: Barton Taylor )

Under the campaign group's bid, 40 per cent of the 79 units in Sirius would be retained as social and affordable housing (10 of those for aged residents) and the remaining 60 per cent sold at market value.

Mr Carter said SOS did not think the building was worth the $100 million price tag, but were "happy to pay that" if the money went to social affordable housing.

"But [social housing] not in the back blocks of Sydney, you know — 30, 40, 50 kilometres from the jobs and opportunities."

Ms Demetriou's apartment will be set aside for when a young woman with her family are in need.

"So young women like Myra who are strong and fearless, and really the face of the Sydney we know and love, the city of the fair go, can live here and her dreams realised just like Myra has helped us realise the dream of saving Sirius," Mr Carter said.

This is a "good deal" for the people of New South Wales, Mr Carter said, and urged the Government to get on board.

"I ask the Government to stop playing petty culture wars and party politics."

NSW Finance Minister Victor Dominello said it was the Government's "clear preference to return the skyline to Sydney".

"However we will not make a decision on that until we first receive responses from the market," he said.

"We encourage responses from across the market, including SOS. The ultimate sale price will be driven by the market."

In July 2017 the Land Court ruled that the Government's decision not to heritage listed was invalid — a decision the NSW Government will appeal.

Myra will leave Sirius on February 1.