The inquiry which will help decide whether the £271m revamp of Anglia Square goes ahead is under way.
The next four weeks will see those for and against the Norwich shopping centre's redevelopment present evidence to a planning inspector at City Hall hearings.
The proposals, by Columbia Threadneedle and Weston Homes were approved by Norwich City Council in December 2018.
The plans include more than 1,200 new homes, including in a 20-storey tower, a hotel, cinema car parks and new shops.
But critics had objectors due to the massing and height of the revamp - and its impact on the historic city skyscape, including Norwich Cathedral.
While Norwich City Council officers had conceded harm would be done, they said it was outweighed by the social and economic benefits.
But, at the request of opponents, including national heritage watchdog Historic England, the matter was called in by the government.
That has triggered this planning inquiry.
Following it, the planning inspector will make a recommendation to local government secretary Robert Jenrick as to whether the scheme should go ahead or not.
Mr Jenrick can choose to follow that advice, of reject it.
The days ahead will see evidence presented on a range of issues, including the impact of the development on the rest of Norwich, its viability, the amount of affordable housing, the impact of traffic and air quality.
Those giving evidence in support of the inquiry include the applicants and Norwich City Council, which has spent £350,000 on lawyers and legal advice.
Historic England, SAVE Britain's Heritage, the Norwich Society, the Norwich Cycling Campaign, and the Cathedral Magdalen and St Augustine's Forum are among objectors seeking to persuade the inspector to recommend that the scheme is not given the green light.
The morning session was mainly taken up with establishing a timetable for the inquiry and to reach agreement on which witnesses will be available on each day.
MORE: The battle for Anglia Square: White elephant or economic boost for Norwich?
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