The Brutalist style of Sheffield's Park Hill estate has divided opinion in the city for decades.
The 1960s concrete block has been hailed as the most ambitious inner-city development of its time and a visionary piece of modernist architecture.
But by the 1980s it was being condemned as an eyesore, having become dilapidated and notorious for drugs and crime.
English Heritage surprised Park Hill's critics by giving the entire complex Grade II-listed status in 1997, making it Europe's largest listed building and preventing it from being demolished.
The decision was hailed by those who regarded it as a building of architectural importance, and the structure is now being given a £134m makeover by developer Urban Splash.
Taking on the contract in 2008, the firm accepted Park Hill had flaws, but said it was "better than a lot of the mediocrity that is defining our cities in their renaissance race".
It added: "Besides, getting rid of it is not a sustainable solution, not when it can be saved, repaired and made good again."
Phase one of the project is complete and has now been shortlisted for the Stirling Prize, the Royal Institute of British Architects' highest accolade.
The architects have kept the structure of the building in place and the wide, long walkways dubbed "streets in the sky" remain, but the external brickwork has been replaced with bright aluminium.
Judges said the reinvented building "stands as a beacon for imaginative regeneration, quality mass housing and the bold reuse of a listed building".
In true Park Hill style, reaction to the announcement has been mixed.
Former Liberal Democrat council leader Paul Scriven has criticised the renovation from the start.
He said: "I'm still of the view that you can't polish a turd, to put it bluntly.
"This is a set of London luvvies who have wafted into Sheffield and wafted out - they have looked at it with rose-tinted glasses and thought part of it is worthy of an award.
"At the same time the first phase isn't sold, they have been on sale for nearly a year-and-a-half.
"The whole scheme is a financial and aesthetic mess. What Sheffield's going to be left with? A half-finished project."
Reaction on Twitter has been largely positive, though one user criticised the project's "infantile bright colours" and another said it was "possibly the most ugly British building ever, even renovated".
James Mills, who lives at Park Hill with his wife Emma, disagrees.
He said he thought the building was "beautiful".
Mr Mills, who works in the architecture industry, said: "I suppose I am enthusiastic about it because, to me, it's what old buildings need. They have turned quite a dark building into quite a light one.
"I know that some people don't like that contrast Brutalist style but when you offset it with the colours that are shown now, you marry two aspects and I think the contradiction that you have got really makes it an eye-opener."
Another resident, Catherine Fletcher, a lecturer at Sheffield University, said people were fascinated by the estate.
She said: "People who have lived in Sheffield for quite a long time have a mixed feeling about the flats.
"There's a bit of cynicism but anybody who knows anything about architecture thinks they're fantastic."
When completed the scheme, which has received about £30m of government money, will boast 874 flats - a mixture of private and social housing.
About 50 of the 78 completed flats are occupied, however Urban Splash has said it is "pretty happy" with the rate of sales.
The company reported financial problems at the beginning of the year, but said it was committed to the Park Hill project and was preparing to start work on phase two later this year.