Sir Ian Athfield was behind the redesign of the New Zealand Stock Exchange building.

Pipitea House in Thorndon, Wellington, home to the GCSB.

Renowned Wellington-based architect Sir Ian Athfield has died. He was 74.

Athfield Architects associate Rachel Griffiths said Sir Ian died in Wellington Hospital early this morning surrounded by family.

Read more about Sir Ian: * Athfield made a knight (2014) * Wellingtonian Interview Q&A (2009) * Review of Athfield's biography (2012)

Complications from a routine procedure at Wellington Hospital resulted in pneumonia. He was being treated for prostate cancer.

"Ath had been dealing with cancer for some time with his usual stoicism and inappropriate humour," Griffiths said.

"There is ... no-one else like Ath and we are devastated by his passing."

The Athfield family had asked for time to deal with their grief, she said.

No date had been set for the funeral or memorial service at this stage.

A statement released this morning by the New Zealand Institute of Architects announced his death.

"It is with great sadness that we inform Members that Sir Ian Athfield, one of New Zealand's finest architects, has passed away in Wellington," it said.

"Our deepest condolences go out to Ath's family, friends and colleagues. There are few details to share at this stage, but we will notify members of any funeral or memorial service arrangements as soon as they arise."

Athfield, who was knighted in the most recent New Year Honours for his work in architecture, won more than 60 awards for his work.

In a professional career spanning half a century, his stamp was imprinted across Wellington, and with Roger Walker, he was probably New Zealand's leading exponent of modernist architecture.

His most well-known works included the City Library and its nikau palm columns, built as part of the Civic Square redevelopment in the 1980s, and his own sprawling Khandallah house.

He also designed Jade Stadium in Christchurch, which was damaged in the February 2011 earthquake.

Walker said he was "still in shock" on getting the news of Athfield's death.

"I knew he was crook but it seems like it was worse than we all thought," he said.

"He did a lot more than I did ... he made a huge difference to Wellington."

Walker said that despite their supposed rivalry, the pair were closer than many thought.

He remembered first meeting Athfield on a building site in the Wellington suburb of Kelburn.

Athfield told Walker he had brought a client up to meet "the other mad architect in Wellington – to show him I'm not the only nutter in town".

Walker said there were two sides to Athfield – the genius and the flesh-and-blood person, but "the two weren't talking to each other".

Fellow architect Sir Miles Warren said he knew Athfield well, since he was the junior draftsman in Warren's office.

"He enlivened the whole office," he said.

"He was the most marvellously amusing man."

Athfield was "the most creative architect of his period", Warren said.

"All the grand adjectives. He added a splendid topping to New Zealand architecture."

While most of his greater works were in Wellington, Athfield designed a number in Christchurch and further south, he said.

In a book, Athfield Architects , released in 2012 by Julia Gatley, she illuminates how his career was informed and influenced by his home town of Christchurch.

As a young man in post-war Canterbury, he was influenced by an emerging and distinctly local form of "brutalism" that became known as the Christchurch School.

A summer working at Warren & Mahoney in the early 1960s may have informed his most important building - the complex of his homes and offices that flows down a Khandallah hillside in Wellington like a Greek village.

Gatley thought the idea of a home and office in one place might have been influenced by Warren & Mahoney's Cambridge Tce offices, which included a flat for Warren to satisfy planning rules.

Wellington Mayor Celia Wade-Brown has a view of Athfield's architecture from her office above Civic Square. She credited him with changing the face of Wellington.

"Not only the visual effect in the city but also the way more people live and work in the CBD than used to," she said.

Apartments and offices designed by Athfield played a massive part in this, Wade-Brown said, adding that his company Athfield Architects "will go on".

She had known Athfield since the 1990s and would remember him as a man with a "great sense of humour".

"I really liked his warmth, his passion for Wellington."

While he would now not be at his investiture ceremony, he had known of his knighthood, "so that is great", she said.

Athfield will retain his title of Sir. At the investiture ceremony at Government House, likely in May, his next of kin would be invited on his behalf.

SOME OF ATHFIELD'S MOST ADMIRED WORKS: