A £2.7m scheme to turn one of King's Lynn's most important buildings into a community centre and concert hall begins on Monday.
The Friends of St Nicholas' Chapel hope to bring new life to the 600-year-old church, on St Ann's Street.
The roof of the church, at the heart of the old fishing quarter, is being replaced, protecting the carved angels beneath it. Solar panels will be installed on flat roof spaces.
Work inside the building includes new toilets, a kitchen and an open area for indoor markets and performances.
The refurbishment, which is expected to take until May 2015, is a partnership between the Friends and the Churches Conservation Trust.
Broadcaster Loyd Grossman, the chair of the CCT, said: 'The regeneration of the Grade I St Nicholas' Chapel is an exciting chapter in the history of this internationally-important building.
'This is the CCT's third major construction project starting on site this year, securing the future of another world class heritage asset and community space'.
Crispin Truman, the trust's chief executive, said: 'With the support of the Friends of St Nicholas' we have cared for this building for more than 22 years, and are pleased that we are now in a position to address urgent conservation work and introduce new facilities to a high standard.
'The project is a superb example of how local people can, with the support of a national charity, save a valuable part of this nation's heritage at the same time as creating a community resource for the 21st century'.
Adrian Parker, chairman of the Friends, said: 'At last we shall see exciting changes under way that will encourage more groups to use the Chapel all year round, with local management.
'The next challenge is for us also to raise the money to repair the bells and bring them back into use.'
The work will be carried out by contractor William Anelay, which has written to neighbouring businesses pledging to minimise inconvenience. Work will be carried out on site between 7.30am and 6.30pm.
Tony Townend, the firm's managing director, said: 'This project offers us the opportunity to help educate and train local people, who will benefit our specialist area of conservation and restoration of historic buildings.'
When it re-opens, the chapel will be run by volunteers.
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