A klaxon horn was being installed in the iconic building, then home to Canberra High School and now ANU's School of Art and Design. In the event of an air raid, the horn would sound a warning to the city. Fortunately, it never rang.

But School of Art head Denise Ferris is now hoping to draw Canberra's eye again as the heritage building undergoes its first face-lift in 50 years.

On Wednesday, the university will announce $80 million in infrastructure upgrades for the school that will see an extensive refurbishment along with an additional two-storey building take shape next door by 2025.

Ms Ferris says the investment will radically transform how the school operates, putting it on par with major national and international competitors.

Today, the 80-year-old building is alive with new technology; traditional paint and easel just a few doors down from 3D printing and virtual reality.

"Of course there's still no air-conditioning," laughs Ms Ferris, who works out of the enormous old principal's office.

"Our building is beloved and we have great facilities but we're still fitting into an old high school," she says. "We need more space."

Vice-chancellor Brian Schmidt said restoration works would take careful account of the building's heritage value when transforming classrooms and studios.

"[It's] a favourite of many Canberrans," he said.

Once complete, the new building - already nicknamed the "glass box" - will offer more of what Ms Ferris calls "makerspace" with the ground floor likely to cater to more heavy-duty machinery such as the kind used in glassblowing.

Planning will begin next year, construction in 2023 and both projects will be completed in 2025.

The money is for infrastructure only, and an ANU spokesman did not say if any further investment would go into the school's resourcing or programs.

But Ms Ferris said it represented significant support from the university in both the school and Canberra's arts scene.

"Canberra could be the cultural capital of Australia," she said.

"Art and design are expensive but when people are just looking at the bottom line bad things happen. Nationally, we're seeing more art schools cold-pressed into other schools. I'm not concerned about that here."

Professor Schmidt said the project would ensure ANU remained a "world-leader in these important disciplines" and forge a "cultural gateway" with the wider Canberra community as more opportunities opened up for local artists and institutions to collaborate in the new spaces.

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In recent years, Ms Ferris said the school had weathered shifts in funding by focussing more on research collaborations across faculties and adapting to the ANU's flexible double degree structure.

Forging a new design program in recent years had helped keep student numbers stable, at about 500, she said.

"We've managed to hold volume, we haven't gone down even if visual art has a little, design is growing," she said.

After overseeing significant staff turnover as part of a voluntary retirement scheme, Ms Ferris said the school now had more than 30 staff, many of whom were new to the ANU.

"So this is about waving the flag, showing that we don't just make beautiful things," she said.

"We make beautiful things and we have big ideas."