"My breath was taken away by the incredible views," she said.

Those sweeping views, taking in the Sydney Harbour Bridge and the Opera House, are what the NSW government hopes will deliver revenue of $100 million, or possibly more, from a developer when Sirius - home to public housing tenants since 1980 - officially goes on sale on Thursday.

Ms Goward's controversial announcement three years ago that Sirius would be sold - with the proceeds used to build new social housing - has been met with fierce opposition from tenants, community members, architects, the Labor opposition and Sydney Lord Mayor Clover Moore.

Despite a Heritage Council recommendation calls to have the distinctive example of brutalist architecture placed on the heritage register have been rejected, most recently by environment minister Gabrielle Upton in October.

Ms Goward will announce that the new owner will have the option of retaining the existing structure and benefit from its current height.

But cabinet has decided any redevelopment must be smaller, limited to the height of the Sydney Harbour Bridge deck, following concerns about the loss of sight lines to the Opera House and the impact on the character of the local area.

Asked if she would be disappointed to see Sirius razed, Ms Goward said: "I think it depends what it's replaced with.

"There's no doubt it's a part of a memory of Sydney from the last century that people probably do have some affection for," she said.

"But in the end what matters to me is that we are able to build a lot more social housing. This will certainly boost the number of properties that we can build."

In March 2014 Ms Goward announced the plans to sell Sirius and about 290 historic housing commission homes in Millers Point to fund construction of new social housing.

Ms Goward said the "legacy" of the Sirius sale would be "hundreds of brand new homes built for our most vulnerable".

"Improving their lives was always at the heart of this decision," she said. "I have met some of the tenants who have already moved into new homes across NSW and heard wonderful feedback."

The government says more than 700 new dwellings for social housing tenants have been built with money from the Millers Point sales and that 372 are under construction.

"For each Millers Point property sold we are building close to five new homes," Ms Goward said.

Planning minister Anthony Roberts said the Sirius site would be declared a state significant precinct, via an amendment to the policy put out for public feedback until February 16 next year.

"Any new building proposed for the site would need to meet design excellence standards for its architectural, urban and landscape plans so that we can ensure we are creating a great place that fits well with the surrounding area," he said.