If you're coming into Central Sydney on the Harbour Bridge, the Sirius Building is the first – and some would argue best – building you'll see. The views from the apartments inside Sirius are more staggering still. Imagine opening your blinds to see Sydney Opera House perfectly framed by the harbour's azure waters.

Sirius is the brightest star in the sky and the Sirius Building, a public housing project, is rightly named – a highpoint for Australian architecture and for the classless society that the nation perfected in the 1960s and 70s, where every Aussie got a home, and all your neighbours would be round for a barbie and a stubbie as soon as you moved in.

Sirius is one of the most futuristic buildings in Sydney – even to this day. Its 'stacked boxes' look is practical and functional – a nod to Japanese Metabolist 'plug-in city' principals where you could add more bits to a city or a building as you needed. It looks like a place where every flat could have a robot butler. Its curves give it grace and the sans serif font on the name plate next to the front door is so Seventies it makes you think a Ford Granada from The Sweeney is about to fly past at any moment.

Opened in 1980 and designed by Tao Gofers, the building contained 79 flats and 400 residents and functioned well during its short life, winning numerous awards. It was a surprise to everyone when it was refused heritage listing in 2017. Its final residents became unlikely celebrities when the social housing tenants were cleared out the same year. Kelly Moss, Cherie Johnson and especially the last resident, 92-year-old Myra Demetriou, were widely photographed and interviewed. The trio became the human face of the relentless gentrification of Sydney – which has run so rampant that this architecturally significant building could bite the dust for the value of the land it sits on.

Several secretive private developers are bidding to build a new tower here, but MPs, the city's mayor and heritage groups are trying to save the building. Poignantly, Sirius – along with the Opera House of course – is one of Australia's most forward-looking buildings, yet it sits right on top of The Rocks – the oldest part of Sydney, where white European Australia began in wild style 233 years ago, fuelled by a lot of rum.

Sirius is so chock full of Mid-Century treasures that it seems odd to destroy it. There's bespoke Seventies furniture and lighting, paintings, sculptures and murals by Gofers and Penny Rosier that look like cave painting animals from Lascaux. In London, the cognoscenti would snap up a place here, as they have at the Barbican and Trellick Tower. But Sydney does not quite see the value of what it has, nor how it could become a huge tourist attraction, luring in busloads of hip visitors. That's changing – the recent Brutalist Sydney Map from Blue Crow Publishers and the popular @brutalist_project_sydney Instagram feed, as well as prominent local architect Eoghan Lewis' Sydney Architecture Walks (sydneyarchitecture.org), have been educating Sydneysiders about their greatest buildings, like Sirius, and the similarly threatened Reader's Digest Offices and Sydney University Bioscience Building – and giving visitors new ways to explore great architecture around the city. But by the time those in charge wake up from their slumber, it could be too late.

Telegraph Travel revisited the empty and condemned building in January 2019 and it was standing forlorn – though stubbornly intact. Its only residents today are security guards with specific instructions to keep journalists out and some birds nesting on the empty balconies. Come to Sydney and see it while you still can.

Four Brutalist apartment blocks that have fared better

Marina City, Chicago



Marina City looks a little like two corncobs rising above the Chicago River (they even have their own moorings). The buildings graced a Wilco album cover and were designed by Bertrand Goldberg, opening in 1968.

Marina City, like two giant corncobs Credit: GETTY

The Barbican's Three Towers, London

The building in the Ben Wheatley film of JG Ballard's sublime dystopian novel High-Rise is a dead ringer for the Shakespeare, Cromwell and Lauderdale towers that crown London's Barbican. Designed by Chamberlin, Powell and Bon, the towers have always been bourgeoise, and are home to many architects, designers and creatives.

The Barbican Credit: GETTY

Pegasus Villas, Dallas



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Torres Blancas, Madrid Credit: getty

Torres Blancas, Madrid



Madrid's Torres Blancas (White Towers) makes you think of flying saucers, revolving restaurants and the Jetsons. Built at the height of Franco's fascist regime from 1964-8, they were a welcome breath of fresh air. The architect was Francisco Javier Saenz de Oiza.