One of Sydney's most prominent examples of brutalist architecture, the Sirius building at The Rocks, will be opened to the public for the first time in almost 40 years.

The building was built in 1979 for public housing tenants displaced during redevelopment in the area.

In 2014, the New South Wales Government announced it would sell the Cumberland Street block of 79 units, along with a swathe of heritage-listed terraces in nearby Millers Point.

Most residents were moved out throughout 2015, despite their protests.

The future of the Sirius building is unclear after the NSW Government announced plans to sell it. ( Supplied: Barton Taylor )

In July 2016, the Government decided against heritage listing the site despite a unanimous recommendation by the Heritage Council.

The Government's decision not to heritage list the building will be challenged at a hearing at the NSW Land and Environment Court in April.

Now, the brutalist building will be opened to the public as part of Art Month Sydney.

Architect wants a city for all

Architect Tao Gofers will be offering tours of Sirius throughout March, while people will also have the chance to meet some of the last remaining residents.

"We're hoping to get more support from the community by opening up the apartments to the public and educating people about social housing," Mr Gofers said.

"Social housing is about inclusiveness and I don't mean for people who don't have jobs, but for those people who are essential to the running of the city.

Few people still live in the building. ( Supplied: Barton Taylor )

"I am talking about nurses, firefighters, police officers, those people who aren't paid a lot, because if you make them move out west, then they end up spending all their money and time on commuting."

Mr Gofers said he wanted people to realise that the city should not just consist of people who earn millions of dollars and can afford luxury apartments.

"We have such a problem with housing affordability and the Government should be providing social housing in all areas, not just way out in the outer suburbs.

"It's not fair to segregate people."

Tao Gofers' design is one of the most prominent examples of brutalist architecture in Sydney. ( Supplied )

Residents eager to discuss passion for building

Myra Demetriou, 90, is one of three people who still live in the Sirius complex and will be posing for portraits by amateur artists.

Myra Demetriou will be meeting with visitors to the building. ( ABC News: Mark Reddie )

"I will be meeting people in the Phillip Room, which is a beautiful timber room full of these cave-like artworks - it's where people used to come together and talk about their day," she said.

"I have lived in the Millers Point area for 60 years and I hope people coming along for Art Month will take the time to ask me about why I am so passionate about staying in my apartment.

"People from all walks of life should be able to live in the city.

"It shouldn't be an environment of investors and the wealthy because then you start causing divisions, which is dangerous."

Tours of the building will run from March 11 to March 25 as part of Art Month Sydney.