Aberdeen's City Garden Project winner is Granite Web
The winning design that could possibly transform Aberdeen's Union Terrace Gardens has been chosen as Granite Web.
A panel of local business people and politicians had weighed up the designs. Opponents criticised the selection.
Members of the public are being asked if they support the project or want the existing gardens kept.
The referendum ballot closes on 1 March.
Chairman of the jury, Sir Duncan Rice, said: "The Diller Scofidio team had thought long and hard about Aberdeen's special history and unique needs.
"Answer by answer, they overwhelmed the jury with their vision and their sensitivity.
"They are flexible and responsive, and the thrilling concept they have offered will continue to adapt and evolve as discussion proceeds."
He added the winning design was expected to cost less than the project's £140m initial figure.
Charles Renfro, partner at Diller Scofidio and Renfro, said: "The steep competition drove us that much harder to do more research, to understand the site more thoroughly, to dig deeper into our creative reserve and our technical expertise to find a daring, thoughtful and beautiful solution.
"While the City Garden is at the heart of Aberdeen, that current heart has little pulse.
"We feel that we can make it throb and bring life and energy into the centre of town."
John Stewart, chairman of the City Garden Project management board, said: "This design will not only transform the Union Terrace gardens site but our whole city.
"I also believe it will transform the way in which Aberdonians perceive, use and enjoy the city centre.
"This could be Aberdeen's Eden Project, our Guggenheim, and will be a unique space that nowhere else in Europe can offer."
He added: "We promised the public we would deliver an exceptional design and then produce a detailed economic assessment.
"This will be announced shortly so that the public know what the project could look like, how it will be funded and the economic benefits it will bring before making their decision in the referendum."
Malcolm Reading, the competition organiser, said: "This is an exciting outcome and a great coup for the city.
"This ingenious and inspiring design for Aberdeen's key public space gives the city a new social landscape but one rooted in its extraordinarily rich heritage and natural assets."
Bob Collier, chief executive of Aberdeen and Grampian Chamber of Commerce (AGCC), said: "The jury has chosen an innovative and exciting design which could transform the heart of Aberdeen's city centre into a contemporary and usable space.
"The next phase will be the details of the funding package and validation of the enormous economic benefits this could bring to the city.
"This project has the potential to breathe new life in to Aberdeen and to transform it into a city with a 21st Century vision."
Mr Collier said the City Garden Project had the full support of the AGCC.
However, campaign group Friends of Union Terrace Gardens claim the project is wrong economically, environmentally and for the heritage of the city.
Friends of Union Terrace Gardens chairman Mike Shepherd said: "The design is futuristic and would be grossly out of place in the Granite City.
"I suspect the residents of Aberdeen will not be impressed with the Granite Web.
"My opinion is that the chances of the public picking this design in preference to keeping Union Terrace Gardens is in serious doubt. It is an unpopular choice for an unpopular project."
Businessman Sir Ian Wood has pledged £50m to the project.
During a previous public consultation process, 55% of those who took part said they did not support the new development.
But councillors backed taking the plans to the next stage.
If the project proceeds, Aberdeen City Council believes construction could be finished by 2016.