Charles Renfro said the decision to cancel the £150 million revamp of Aberdeen's Union Terrace Gardens was "shocking" and condemned as undemocratic Wednesday's decision by the council to override a referendum of residents who supported the project.
Renfro, whose award-winning New York firm Diller, Scofidio + Renfro has designed buildings and cityscapes across the world, and who prides himself on his Scots ancestry, said: "The political entanglement behind the decision not to move this project forward is really disappointing, not just for me and our architectural practice but more generally for the message it puts out that people in Scotland are so frightened to engage the future."
"It sends the message that Aberdonians are so backward-looking that they're shivering in their boots about anything new.
"I find it completely shocking that despite the public referendum and the majority vote, the Labour council took it upon themselves to up-end that process and throw democracy out on its ear. Individually, many of the citizens of Aberdeen proved to be open to this progressive plan, but collectively fear got the better of everyone. Maybe it's something to do with the group dynamic."
He added: "I have seen projects cancelled in many other places around the world because of funding, but the City Gardens project is the first in our international career that has been driven by pure nostalgia and fear of the future. Opponents have said they are afraid of how its going to be paid for, but given that many prominent business people in Aberdeen stood up and said they would donate millions, my understanding is that this was an ill-founded fear."
The plan to rejuvenate the area was kick-started by a pledge of £50m in funding from local oil services magnate Sir Ian Wood, a donation Renfro said "most cities around the world would have accepted with great fanfare".
He added that in the wake of the council vote against the project this week, he felt like "vowing never to set foot in Scotland again".
First announced in 2008, the plan to overhaul Aberdeen's city centre Victorian-era garden was proposed by Wood in order to bring about "the transformational change our city centre requires and deserves".
The project was also to be funded by a £92m loan from the Scottish Government. The winning design was selected by the project directors following a public exhibition, and was endorsed by a 52% vote in a public referendum in March.
However, a narrow victory by Labour in the May council elections sealed the project's fate. Having made opposition to the plan a key plank of its election campaign, the newly-elected council leadership won a vote on Wednesday to reject the scheme by 22 votes to 20.
Richard Baker, the Labour MSP for North East Scotland, said: "We went into elections on a manifesto commitment to scrap the project and we have honoured that. If [Renfro] and his colleagues don't understand that part of democratic mandate, then I suggest they need to brush up their idea of democracy".