Savills has been appointed by the NSW government to start a public sales campaign, with funds raised used to invest in new social housing across the state.

The Sirius sale is the latest initiative under the NSW government's strategy to fund new social housing close to jobs, education and transport through the sale of former social housing dwellings in Millers Point and The Rocks.

It has attracted significant public comment which has prompted the NSW government to placate concerns by issuing height restrictions.

Located on a 3,647sqm site, the stepped Sirius building form currently comprises 11 storeys tapering down to the north and south. The existing building comprises 79 units of varying configurations with over 70 basement car spaces.

Minister for Planning Anthony Roberts said the maximum height of any building would be restricted to the height of the Sydney Harbour Bridge deck.

"This height restriction will ensure any building approved on the site fits in with the character of the surrounding buildings," Mr Roberts said.

"Any 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.''

Sirius is exclusively listed through Simon Fenn, Stuart Cox, Neil Cooke and Michael Simpson of Savills Australia via an international sales campaign with the opportunity for a variety of uses via the flexible zoning applicable to the site.

According to Simon Fenn, managing director of Savills NSW, Sirius is positioned on some of the most valuable land in Australia and will certainly attract interest from around the globe.

''There is a once-in-a-lifetime opportunity to revitalise this prime site with a range of potential future scenarios including residential, commercial, hotel and retail or a mix of these,'' Mr Fenn said.

"Never before has a building with such unobstructed and striking harbour views within the heart of Sydney been offered to the market. A proposal like this is certainly one in a million," he said.

Sydney has already seen a major renaissance for the CBD core with about $7.9 billion worth of new construction and infrastructure earmarked for the Circular Quay precinct. The Light Rail and Circular Quay Ferry, Bus and Rail Interchange upgrades have added value to the area.

According to Stuart Cox, director, residential site sales at Savills Australia, this is a ''substantial opportunity to secure arguably the most recognised landmark site in one of the world's key gateway cities''.

Sirius is likely to attract significant interest from a range of different development and investor groups, both locally and offshore, that have the relevant development experience, capability and financial capacity to take on this significant project," Mr Cox said.

Minister for Finance, Services and Property Victor Dominello said it is the government's ''clear preference to return the skyline to Sydney, however, we will not make a decision on that until we first receive a response from the market''.

The site is one of many NSW government-owned properties that have been sold to developers. Others include the sandstone buildings in Bridge Street and the GPO, which will become a new Fullerton hotel, once the contract with the Westin group expires next year.