Is this Sydney's ugliest building? Either way, it's started a multi-million dollar price stoush

From the outside it could be described the Harbour Bridge’s ugly step-sister, but these stacked cubes of concrete – dubbed “brutalist” architecture - are at the centre of a multi-million dollar property stoush.

The Sirius apartment complex, social housing with fantastic waterfront views, is part of a NSW government sell-off plan.

The government has earmarked it and other inexpensive housing in Millers Point as sites prime for redevelopment.

But Heritage Council of NSW is considering putting the building on the state’s heritage register, arguing the Sirius is of historical significance because of its links to the union “green bans” of the 1970s.

The fight could delay plans to sell the old Sirius building, but NSW Social Housing Minister Brad Hazzard is standing firm, saying a decision to put a heritage order on the building would reduce its value.

The Sirius was purpose-built, complete with 79 apartments, in the 1970s. While it has spent its entire life as social housing, it comes complete with multi-million dollar views out across the Opera House and Harbour Bridge.