Some call it “the champagne cork”, “the wedding cake” or “the shuttlecock”.

To Newcastle City Council veteran Graham Barrie, it’s always been the “Roundhouse”.

“Even back in the early 80s, our staff indoor soccer teams were called the Roundhouse Rebels and the Roundhouse Rats," Mr Barrie says.

Whatever your name for it, the iconic building celebrates a milestone on Friday – 40 years since its official opening on June 23, 1977.

Mr Barrie had already been with the council for 10 years when the building opened and says it has always been a source of pride.

"Everyone was excited about having this round building there," he said. "It was this unique design and there was no other building in Newcastle like it."

Newcastle Herald history columnist Mike Scanlon said the then Newcastle council deserved credit for having “the foresight to create something totally different back then, something that might, over future decades, still seem modern. As such, I think they succeeded admirably”.

“When finished, although still a controversial design, the innovative building made a bold statement of a city on the march. Its colour matched City Hall's stonework and its deep recessed windows cut down the sun's heat,” Scanlon wrote in 2015.

“The radical circular building was also an engineering marvel. To combat the very high water table, erecting the structure first required virtually building an underground dam and using a mixture, (from memory) of fly ash (from the burning of coal at power stations) and an extremely quick-setting cement slurry to prevent any collapses into the excavation.”

The site was earmarked as early as 1950 for development to ease overcrowding at City Hall.

The then Newcastle Town Clerk, Bill Burges, said at the opening of the city's new circular administration building on June 23, 1977, that it had taken five years of negotiation before any land sale was even considered.

“And even then, the land's owners, the firm of Fred Ash Ltd, would only consent to sell if Newcastle council also bought its 1905 Hunter Street store and its "new" (1925) Burwood Street warehouse,” Scanlon wrote.

The council agreed. Architects Romberg & Boyd combined with Wilson & Suters to tackle the project. The acquisition plan was completed in May 1969 and work began in April 1972 to construct eight storeys above ground plus three levels of basement parking.

Newcastle Lord Mayor Nuatali Nelmes said it was one of the city's landmarks.

"It's testament to the building's original design that it still looks so striking and unique, 40 years after it first opened,” she said.