The tower has received the 2017 Prix du XXe siècle, or Prize of the 20^th Century directly translated from French, which is awarded annually to Canadian buildings of national significance completed between 1967 and 1990.

It is awarded by the Royal Architectural Institute of Canada, in partnership with The National Trust for Canada.

Mr Andrews’ practice, John Andrews Architects, was invited to design the project during his 15-year stay in Toronto after railway company Canadian National vacated the land.

“I’m really quite moved [by the award],” he said.

“It was almost 50 years since I left Canada and it takes me back to what was the most productive part of my architectural life.”

The Harvard graduate completed the design in 1973 with the help of Webb Zerafa Menkes Housden Architects and an engineer from Montreal.

“You work with an engineer because an architect can’t calculate something like that – it’s tensioned into the bedrock, down below the lake,” he said.

He enclosed the telecommunications equipment in plastic to prevent ice from falling to the street below during Toronto’s freezing winters, while the heating exhaust from the restaurant kept the spire ice-free.

“They wanted the tower to broadcast images into the United States and you can get further if you use a flat surface like water to bounce the signal,” he said.

The building was completed in 1976, becoming the world's tallest free-standing structure and world's tallest tower at the time.

The CN Tower is now the third tallest tower in the world, declared one of the modern Seven Wonders of the World by the American Society of Civil Engineers in 1995. 

After his return to Australia 50 years ago, his designs included the Cameron offices at Belconnen in Canberra, the King George Tower in Sydney, the Sydney Exhibition Centre in partnership with Philip Cox and Melbourne’s World Trade Centre.

Moving to Orange 10 years ago, he has designed options for the former base hospital site and said his favourite building was a new home in west Orange built for an elderly woman who liked to entertain.

He said Orange has reached the stage of urbanisation. 

“I’m interested in people and how they live and how they communicate and how they develop, and just the notion of what architects can do for people,” he said.