IS IT ugly and deserving of a wrecking ball? Or iconic and in need of protection?

It depends who you ask.

But for now, Sydney’s Sirius building — which has been used for public housing since it was built more than 30 years ago — appears to be living out its final days next to the iconic Harbour Bridge, in The Rocks.

The Cumberland Street apartment block is under threat from NSW Government plans for redevelopment, with most tenants having already moved out.

Hundreds of protesters have opposed the plans to replace the 1979 building with apartments boasting million-dollar views and price tags to match.

But their calls to save the building have so far fallen on deaf ears, with a heritage listing bid for the harbourside building ultimately rejected by the government.

The building is arguably the worst eyesore on one of the world’s most spectacular harbours. So why are so many people fighting to protect it?

‘IT REPRESENTS THE SOCIAL MIX AND SOUL OF THE CITY’

Sydney’s Lord Mayor and NSW opposition members joined hundreds of protesters in a march from Circular Quay over the weekend, demanding one of the city’s most controversial buildings be saved from demolition.

Hundreds of protesters marched from Alfred Street, around the Quay, meeting at the base of the brutalist building on Saturday morning.

The vocal crowd, flanked by police officers, were addressed by several opponents of the building’s slated demolition, including Lord Mayor Clover Moore and opposition planning minister Michael Daley.

“If the government applies this policy to other inner city areas, it will destroy the social mix — the very soul of city — and we will fight that all the way,” Ms Moore said from the back of a truck in front of the building.

“This housing is needed just as much now, or even more, because the majority of social housing residents in Millers Point have already been dispersed.”

‘IT’S ABOUT THE RESIDENTS WHO ARE BEING EVICTED’

The mixed-bag of protesters included unionists, architects and social housing advocates.

The CFMEU granted a Green Ban over the building earlier this week, in an attempt to stall demolition plans.

Michael Daley warned the Baird government any attempt to tear down the building would be met by fierce opposition.

“We’re here to say to Mike Baird, if you try and cheat the people of Sydney out of the Sirius building, when you come down here with your developer and your banker mates, we’ll be waiting,” Mr Daley said.

Architects Olivia Savio-Matev and Hugo Raggett said the Sirius building held more than just architectural importance in Sydney.

“We’re here to support and save the heritage architecture of Sydney, but also to support the residents who are being evicted.

“I think the government’s stance on this building is purely a money grab.”

‘IT HAS A UNIQUE HISTORY’

Leading the charge to save the building of brutalist architecture is the National Trust’s advocacy director Graham Quint.

“They’re dramatic and they’re meant to make a statement,” Mr Quint told news.com.au.

“I don’t know whether ‘beautiful’ would be the word, but not everything’s meant to be beautiful.”

The Sirius building had a unique history, said Mr Quint, built specifically for housing commission tenants turfed out of harbourside suburbs when the area was being redeveloped in the 1960s.

Far from blocking views of the harbour it actually “steps down” to reveal a wide sweep of Sydney, said Mr Quint. Any replacement could be even bigger.

The Sirius building is not the only inner-city public housing on the chopping block, with the NSW Government also selling houses in Millers Point to private buyers.